E.ON is selling its Norwegian oil and gas assets to Russian billionaire Mikhail Fridman’s German business DEA in a deal worth $1.6 billion (£1bn), as speculation continues over the future of its UK North Sea assets.

The deal comes days after DEA, which Fridman’s vehicle LetterOne bought from E.On rival RWE earlier this year, sold 12 Southern North Sea gasfields to Jim Ratcliffe’s Ineos group in what was reported to be a £500m deal.

It highlights the continuing international appetite for picking up North Sea assets, following Ithaca Energy’s landing of a $66m investment from Israeli conglomerate Delek.

The L1 fund emerged as the frontrunner to buy E.ON's Norwegian North Sea assets after the Russian was forced to sell his UK North Sea assets as a result of Western sanctions over the Ukraine crisis.

E.ON meanwhile has been reported as expecting to net “up to $2 billion” from the sale of all its oil and gas assets in Norway, the UK North Sea and Algeria.

Its Norwegian E&P business had output of 16.35 million barrels of oil equivalents (mboe) in 2014., while the UK unit's output stood at 6.02 mboe. The utility hinted at further action by saying it would "provide an update in due course" on the UK assets.

E.ON said last December it was restructuring to focus on renewable energy. The power giant announced plans to split in two and spin off most of its conventional power generation, energy trading and oil and gas exploration and production businesses.

The company told investors that the slimmed down core group would focus on renewables, distribution networks, and customer solutions.

The decision put a question mark over the future of the North Sea exploration and production business E.ON has developed in recent years.

The business has stakes in seven fields off Scotland and seven off England and exploration interests West of Shetland.

The unit has a base in Aberdeen and employs 150 people in the UK.

In July 2013 E.ON pulled out of the Pelamis wave-power research project in Orkney over concerns that development of the technology had been too slow.

Michael Sen, E.ON's chief financial Officer, said: "The successful sale of our E&P business in Norway is a landmark transaction in the sector." Under its restructuring plan, E.ON will spin off its energy trading, oil and gas activities and most of its power generation next year into a new company called Uniper.

E.ON’s Norwegian unit has stakes in 43 licences but most are exploration assets, only a handful are in production and none is operated by E.ON. Its main production fields include Njord, operated by Statoil, and Skarv, operated by BP.

Shares in E.ON turned positive after the sale news and were up 2.6 percent in early trading.

The purchase by L1, whose energy fund is headed by former BP boss John Browne, signals a push by the Russian oligarch to expand his fund's oil and gas portfolio.

Thomas Rappuhn, DEA’s chief executive, said: "This acquisition in Norway is a perfect fit to our renewed business strategy." Mr Rappuhn said the company would look for further acquisitions in Europe and North Africa.

The deal, which is subject to the regulatory approval of Norwegian authorities and the European Commission, is expected to close by the end of the year, a spokesman for E.ON said.

Norway's oil minister said he welcomed the fact international companies were interested in investing in the country, adding that the application for approval of the deal would be handled in ‘the usual way’.