Sebastian Coe, chairman of the London Olympic organising committee (LOCOG) and a gold medal winner, said people were "overwhelmingly positive" about the buildup to the greatest show on earth, while London Mayor Boris Johnson told critics to "put a sock in it, fast".

Their comments were unlikely to make the controversies go away, however, with industrial action by passport officials on the eve of the July 27 opening on the minds of thousands of visitors and athletes arriving in Britain at the last minute.

"This is a challenge, this is a very, very tough project," Coe told BBC radio in an occasionally tetchy interview.

"No city is challenged in the way a city is challenged when it delivers an Olympic Games."

Asked whether a "negative narrative" was taking hold, Coe said: "I'm neither cavalier about this or overly sanguine. It comes with the territory."

The biggest single problem in the runup to the Games has been the shortage of guards to secure venues, after the company G4S (GFS.L) failed to meet its staffing targets and thousands of extra soldiers were recruited to fill the gaps.

Transport delays also loom over the event, with border officials going on strike on July 26 and train drivers in central England walking out from August 6-8 during the final week of the Games.

Athletes as well as visitors could be caught up in the disruptions, with Australia's cycling team due to arrive in Britain on July 26.

"We are in discussions with LOCOG and they are aware of it," said Nick Green, Australian chef de mission. "If it does eventuate I am sure LOCOG will have some plans in place to ensure the athletes have a safe passage through."

"ENOUGH WHIMPERING"

Mayor Johnson was typically blunt in his appeal to the public and media to concentrate on the positives.

"Oh come off it, everybody - enough whimpering," he wrote in the Sun tabloid.

"Cut out the whining. And as for you whingers, put a sock in it, fast. We are about to stage the greatest show on earth in the greatest city on earth, and if you believe much of the media we are all in the grip of paralysing stage fright."

Coe said he was looking forward to the sport, as more than 16,000 athletes from 204 countries descend on London and seek to turn four years of hard training into medals.

The Olympic torch nears the end of its 8,000 mile journey later on Friday when it arrives in the capital.

"The torch is arriving in London today, the sport will start literally hours after the opening ceremony," he said. "That's what we have spent seven years delivering and I think the teams have done a pretty good job."

The emotion of competition will be matched by the human drama behind many athletes contesting medals in 2012.

Some of the biggest names in sport are already in Britain preparing for their big day, including Jamaican Usain Bolt, the sprinter who stole the show in Beijing in 2008 by destroying the world 100 and 200 metres records.

Less recognisable but with a story no less compelling, Libya's small team will compete in judo, swimming, athletics and weight-lifting despite the country's Olympic committee president being kidnapped by gunmen in Tripoli on Sunday.

On Friday, French athlete Nour-Eddine Gezzar, who had been selected to represent France in the steeplechase, was provisionally suspended after failing a dope test.

SPONSORSHIP SPAT

Headlines about the sometimes bumpy road to the opening ceremony have been concentrated largely in the local press, but they have also spread further afield.

German weekly Der Spiegel, in its latest edition published earlier this week, was highly critical of everything from the rain to infrastructure. "London and the Olympic Games are not made for each other," it opined.

In Britain on Friday, attention turned to the issue of sponsorship when Coe was asked whether people would be allowed to wear a T-shirt emblazoned with insignia for Pepsi, even though its rival Coca-Cola (KO.N) is a sponsor.

Coe said he thought it probably would not be permitted, but LOCOG later clarified his remarks.

"Any individual coming into our venues can wear any item of clothing, branded or otherwise," said a spokesman. "The only issue is if large groups come in together wearing clearly visible branding/marketing." (Additional reporting by Stephen Brown in Berlin, Marie-Louise Gumuchian in Libya, Julien Pretot and Matt Falloon, Alan Baldwin and Tim Castle in London; Writing by Mike Collett-White; Editing by Alison Williams)

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