Russian billionaire Mikhail Fridman's LetterOne fund has asked Britain to delay an October deadline to sell its North Sea assets after a first round of offers disappointed, several sources said.

The British Energy Ministry in April gave Fridman six months to dispose of oil and gas fields LetterOne had acquired from German utility RWE or see the their licences revoked as the West tightened sanctions against Moscow over its role in Ukraine.

The sale process, which is advised by Morgan Stanley, has attracted interest from several buyers, including private equity funds which have built up resources over the past year for acquisitions in the sector, banking sources said.

The offers, which were submitted in July, nevertheless fell far short of LetterOne's target price of up to $1.2 billion, with the highest offers coming in at around $750 million, according to several sources close to the process.

The fund hopes to be able to re-tender the assets later this year. The current deadline expires on Oct. 20.

"LetterOne are talking to the UK government trying to defer the process and get more time in the hope of getting a better price," a banking source said.

The North Sea assets comprise of 11 oil and gas fields, including a 70 percent stake in the Breagh field which produces 3 percent of Britain's annual gas output.

LetterOne would not comment.

The Department for Energy and Climate Change told Reuters there was no change in its Oct. 20 deadline.

Many oil and gas companies have been trying to sell assets in the North Sea to boost their balannce sheets following the more than halving of oil prices since June 2014.

The merger and acquisition market has only seen a relatively small number of transactions as oil price volatility has kept buyer and seller valuations apart, according to bankers.

Consultancy 1Derrick said last month that so far this year there have been 20 transaction in the UK North Sea, including Total's sale of its 20 percent stake in the Laggan Tormore project for 565 million pounds.

Offshore