But the ballyhoo had no sooner died down after the signing of the gas terminal deal than the alleged Spanish partner disowned it and the mysterious outsider involved vanished, leaving Ukrainian officials humiliated and embarrassed.

The deal at the center of the high-profile signing ceremony on November 26 had seemed to tie in Spain's Gas Natural Fenosa as the main investor in building a liquefied gas (LNG) terminal on the Black Sea Coast - a strategic project for which the former Soviet republic has long been looking for foreign support.

But, to the surprise of Ukrainian officials including Prime Minister Mykola Azarov and Yuri Boiko, the country's powerful fuel minister, who both attended the ceremony, the Spanish energy company swiftly denied joining any consortium.

In the ensuing confusion, attention focused on the identity - and role - of the Spanish-speaking man who had signed on behalf of the company - a bald figure with a tufty beard who was well-known as a middle-man in deals between Spanish companies and Ukraine.

He was identified by Ukraine's state investment agency - whose chief Vladislav Kaskiv was co-signatory of the agreement - as Jordi Sarda Bonvehi, who Reuters has learned is a 43-year-old ski instructor-turned-businessman from the Barcelona region.

But Gas Natural said Bonvehi did not work for the company and, in a statement on November 28, suggested it might consider taking legal action.

Bonvehi himself slipped away after the ceremony, left the country and his whereabouts are unknown although he was said to be in Spain last week.

Speaking by mobile phone with Reuters, a man who identified himself as Bonvehi conceded he had not been authorized to sign for Gas Natural. "I thought I could sign it and then settle it with the company," he said.

In subsequent telephone conversations with Reuters in Spain, apparently the same person declined to answer questions by telephone, but said that at some point he would make a statement.

Collapse of the LNG terminal construction deal, particularly in such humiliating circumstances, is a setback for the Kiev government which is desperate for alternative energy sources to wean itself off dependency on Russian gas.

Apart from figuring in energy discussions, Bonvehi has traveled to at least two parts of Western Ukraine where he sought to interest local authorities in waste-recycling projects, local officials say.

Neither deal came to anything, they said. "We had a visit but it came to nothing. We talked and that was all. There was not a single phone call from them afterwards," said Viktor Dobrorez, who heads the local investment department in the town of Khmelnitsky.

Gas Natural, a leading LNG operator with stakes in liquefaction plants in Egypt and Qatar, says its engineering unit carried out a viability study into the LNG project at the behest of the Kiev government. The company says such studies do not necessarily entail final participation in a contract.

In a press statement after the signing, the Ukrainian state investment agency initially identified the Spanish signatory as a Gas Natural executive called Jordi Garcia Tabernero.

Gas Natural immediately denied this too, saying that Tabernero, the company's managing director of communications, had not been in Ukraine then. At the time of the signing, he had been in his Barcelona office, it said.

It has declined to make any further statements on the matter beyond what it said in the immediate aftermath of the signing.

Ukrainian officials now accept the deal is no longer valid and had been signed with an unauthorized person. Bonvehi, they say, acted "at his own discretion" and exceeded his authority.

AMBITIOUS PLANS

The planned LNG terminal, to be built near Odessa, would receive liquefied gas by tanker from foreign suppliers and then re-gasify it for feeding into Ukraine's pipeline network.

The collapse of the deal is all the more embarrassing because the Kiev government often uses its LNG potential as a card to play in talks with Russia as it strives for a more equitable relationship and cheaper gas.

Ambitious LNG plans foresee imports of about 10 billion cubic meters of gas in 2018 when the planned onshore terminal would be up and running - roughly a quarter of Ukraine's current gas consumption levels.

Kaskiv, head of the state investment agency whose job is to identify foreign investors for key national projects, had been seeking foreign financing for some time for the LNG project.

A 39-year-old former journalist who was once a foreign investment adviser to jailed ex-prime minister Yulia Tymoshenko, Kaskiv was named to head the agency in December 2010. But despite a world-wide road show banging the drum for Ukrainian projects, his agency has notched up few successes.

Kaskiv said he feared the collapse of the deal would hand a "trump-card to opponents" of LNG development in Ukraine - meaning Russia - though officials say they will continue the search for foreign investors despite the setback.

Kiev-based diplomats said they had been surprised when the signing with Gas Natural was announced since a deal on the highly ambitious project was not known to be near.

In the initial post-signing euphoria, Kaskiv said the deal provided for Gas Natural taking the lead in a group of foreign investors who would provide over 90 percent of the financing for the LNG terminal, the first to be built in Ukraine.

Prime Minister Azarov, seizing on the moment to symbolically launch a new land pipeline to connect with the planned terminal, spoke of a "really historic moment ... the first real big step towards energy independence".

But within a short time, Gas Natural came out with a flat denial of any participation. "Gas Natural has not signed any contract to invest in an LNG plant in the Ukraine, nor are we leading any consortium to develop such a terminal ... nor are we studying anything along these lines," it said.

SKI-INSTRUCTOR, MIDDLE-MAN

So where did the mystery Spanish signatory appear from? And why did the Ukrainian side think it had the grounds for a deal?

In Spain, family members said Bonvehi, who left home when he turned 20 and became a ski instructor in Andorra, moved to Ukraine 10 years ago after visiting as a tourist and marrying a Ukrainian.

His father, Joan Sarda, who still lives near Barcelona, was quoted by a local newspaper, Regio7, as saying his son set up two local businesses in Spain in 2008. Both concerns, which are registered as being involved in real estate, had been inactive for years, the father said.

"Jordi ... was never interested in business, neither in mine nor in that of his brothers or anyone else's. He never demonstrated any interest in business whatsoever," the father was quoted as saying. Joan Sorda could not be reached independently by Reuters for comment.

Speaking to Reuters, Bonvehi's brother, Oriol Sarda Bonvehi, said Bonvehi had visited his parents on November 30 and then disappeared again. "He never told me anything about it (his business). But to reach as far as he did he must be good at business, no?"

People who have followed the case in Ukraine say Bonvehi worked as a go-between in deals for Spanish companies and the Ukrainian authorities and is listed as general director of the Ukrainian branch of Grupo Hera, whose specialty is given as waste-recycling on its website.

The Hera company name is still listed on an intercom panel at the three-storey building in Kiev from where it operated. But the first-floor office is occupied by another firm which says it has nothing to do with Hera.

Bonvehi has traveled around Ukraine on business ventures and in September attended the YES conference, an annual economic forum in Yalta, where he took part in LNG discussions, energy officials say. A photograph from the conference shows him seated at a round table opposite Fuel Minister Boiko and Kaskiv.

"PRESSURE OF CIRCUMSTANCE"

Speaking to Reuters on November 30, Kaskiv said Bonvehi emerged as a signatory at the Kiev ceremony in the absence of any other Spanish officials. He now admits though that Bonvehi had no authority to sign for Gas Natural.

Ukrainians say that no money was lost - apparently ruling out immediate financial gain as a motive. They do not talk of duplicity, only of a "misunderstanding".

"It (the signing) was the pressure of circumstance because at the last minute it became clear that there was no-one from the Spanish side who could, as far as we understood, sign the document," Kaskiv said.

"This person did not simply appear out of nowhere. He took part in negotiations and clearly positioned himself as a participant in the negotiating process in the preliminary stages when other official persons were there," he said.

But he admits Bonvehi did not have the legal right to sign for Gas Natural. "There was no legal document that would have authorized him to be the signatory of the agreement. But given that he had been participant in all preliminary stages of negotiations - things were clear for us," he said.

Pressed on how Bonvehi had therefore been allowed to sign, Kaskiv said: "It was a mistake ... We discussed this question with him just before the signing and in the course of this discussion we took this decision (to allow him to sign)."

On the Ukrainian side, Kaskiv's role is likely to come under scrutiny in a government commission of inquiry which was set up on Wednesday.

Speaking to Reuters on Wednesday, he suggested that the Ukrainian side were still hoping for a top-level meeting with Gas Natural executives to clear things up.

"We have not received any clarifications beyond the information that they (Gas Natural) had not taken any decision at that particular time and that they are carrying out an investigation among themselves to clarify relations with Mr. Bonvehi," Kaskiv said.

Was there any duplicity? "I know there is no doubt that he (Bonvehi) took part in negotiations at various stages. As for what happened at the time - we are waiting impatiently for some clarification from the Spanish side."

(Reporting by Pavel Polityuk and Olzhas Auyezov in Kiev,; Tracy Rucinski in Madrid and Braden Phillips in Barcelona; Writing by Richard Balmforth; Editing by Giles Elgood)

• A Permanent Economic Emergency