Gazprom raised the pressure on TNK-BP, the Russian oil venture 50 per cent owned by BP, saying Russia could again consider revoking its licence to the Kovykta gas field if talks did not progress on selling control of the project to the state controlled gas group.

Alexander Medvedev, Gazprom’s deputy chief executive said: “We cannot wait endlessly.
“We received a signal from the Natural Resources Ministry that if this continues they could return to the question of annulling the licence. The ball for closing the deal is in TNK-BP’s court.”

Mr Medvedev’s comments came as TNK-BP said Russia’s tax service had issued it with a new claim for 2004-2005. The company said it had received the claim at the end of last year and was co-operating with the authorities.

TNK-BP, which is also 50 per cent owned by a trio of Russian billionaires, has come under mounting pressure in recent months, sparking new speculation that Gazprom is seeking to buy out its Russian shareholders as the state tightens its grip on the energy sector.

Police raided its Moscow offices last month, ostensibly in connection with an industrial espionage case by one of the company’s employees. But one banker familiar with the matter suggested the incident was connected to manoeuvring by one of its Russian shareholders ahead of a possible sale.

TNK-BP’s Russian shareholders have repeatedly denied they want to sell, but a moratorium on share sales by its owners expired at the end of 2007.

The venture agreed last summer to sell its 62.9 per cent stake in its east Siberian Kovykta gas field to Gazprom for $700m-$900m. The deal came after months of government threats to revoke its licence for the project over claims it was not producing enough gas.

But completion of the sale has been repeatedly delayed amid wrangling over the price, and over the terms of a broader asset swap deal with BP and TNK-BP that would give TNK-BP an option to buy back a 25 per cent stake in Kovykta.

Mr Medvedev had said last month that he hoped the deal would be closed by the end of April. On Wednesday, he said, Gazprom was “disappointed that technical matters are turning out to be so complicated”.

He said Gazprom would not enter a project which is under threat of losing its licence, which he said the Natural Resources Ministry had “every right” to take away.

TNK-BP paid $1.4bn in back taxes for 2002 and 2003 in November 2006.

Mr Medvedev also said Gazprom would start exports of liquefied natural gas from its Sakhalin-2 oil and gas venture at the beginning of 2009 as planned.

Royal Dutch Shell was forced to sell control of Sakhalin-2 to Gazprom in 2006 following government allegations of environmental violations at the venture.