Arik Air - the only Nigerian airline flying to Britain - said slots it had leased from Lufthansa's (LHAG.DE) British unit bmi at London's Heathrow airport were about to expire and it was now facing unspecified "restrictions".

"Whilst it is regrettable to have to suspend our services between Abuja and London, we simply could not continue with the route due to the restrictions placed upon us in accessing arrival/departure slots into UK airports," Arik's chief executive Michael Arumemi-Ikhide, said in a statement on Friday.

He did not spell out who was imposing the restrictions on the company.

But a similar row over landing slots and ticket pricing between Nigerian and British authorities in November almost grounded all flights between the two countries.

"It is an unfortunate situation and one that we felt was being resolved at government level and we hoped that an agreement would have been reached before the start of the summer schedule," said Arumemi-Ikhide in the statement.

The suspension did not affect Arik's flights between London and Nigeria's commercial hub Lagos.

Landing slots at Heathrow, one of the world's busiest airports, are popular and over-subscribed. Nigeria's government and Arik Air want the British government to help it get more slots at Heathrow but UK authorities have said it is not their responsibility under a joint agreement between the countries.

Britain and Nigeria have a bilateral air services agreement BASA.L which allows them each 21 equal flight frequencies between the two countries, which their airlines can use.

The UK argues that Nigeria is entitled to 21 flights to the Britain a week but it can not guarantee them 21 landing slots at Heathrow. Other London airports have slots available.

Arumemi-Ikhide said Nigeria gave UK carrier "unfettered access" to the slots at Nigeria's Abuja and Lagos airports. "However, this is not reciprocated in the UK," he added.

The Nigerian aviation ministry was not immediately available for comment on Saturday. It warned last year that it would not "stand idly by while Nigerian flag carriers are unfairly treated when BASA agreements clearly state otherwise."

Nigerian authorities fined BA and Virgin Atlantic VA.UL a total of $235 million for alleged price fixing in November, which both airlines deny.

The aviation minister has claimed BA flights between London and Nigeria we more expensive than flights covering a similar distance between Britain and Ghana.

Searches on the BA website show flights to Ghana are significantly cheaper than to Nigeria in business class and first class but not in economy class.

(Reporting by Joe Brock; Editing by Andrew Heavens)

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