Alexander Temerko, a leading oil industrialist in Britain, has launched a stinging attack on BP, accusing it of abandoning its lead role in the North Sea in favour of championing the interests of Russia.

With the European Union threatening new sanctions on Russian, the director of Newcastle-based offshore engineering and construction group, OGN, says the British-based oil company has lost interest in its home base since taking a 20% interest in Kremlin-controlled Rosneft.

"BP used to be a strong voice for the North Sea but now it is very, very soft. The only time you really hear the voice of BP is when it is warning about sanctions being imposed on Russia," said Temerko.

"BP was a champion of North Sea investment but it has gradually sold off many of its assets to foreign companies such as Apache and Talisman while putting its money into Russia with Rosneft. You should call it Russian Petroleum not British Petroleum."

Temerko is himself a former Russian national and was deputy chairman of Yukos, the now-dismantled Russian oil company established by oligarch and political dissident, Mikhail Khodorkovsky.

He fought a successful court battle to stop being extradited back to Russia on what he claimed was trumped up fraud charges and has since established himself as a top British industrialist and Tory donor.

Former shareholders in Yukos have recently won $50bn (£30.1bn) in damages from the Russian government after an international court in the Hague ruled the officials under President Vladimir Putin deliberately set out to bankrupt and nationalise the business.

The assets have largely ended up in the hands of Rosneft, and there have been threats that the British company might be sued by those same former Yukos shareholders.

BP admitted it had sold off many local assets but said it was untrue that it was abandoning the North Sea. In fact it was one of four key global locations where it was concentrating its spending.

"We are investing in new developments in the UK. BP and our partners expect to invest more than £7 billion in the North Sea over the next five years. We're also still looking for new opportunities. We were awarded interests in 14 new exploration blocks last year – our most successful UK licensing round since the 1990s," said a BP spokesman.

He pointed out Trevor Garlick, one of its executives was a co-chair of the Oil & Gas UK lobby group while Bob Dudley its chief executive's personal views on Scottish independence had been widely quoted. In February, Dudley said he did not want to see Scotland "drifting away" from the UK.

Temerko denies he is motivated by feelings of anger against BP over the Yukos affair and still criticises the British oil company over what he argues has been its low profile in the Better Together campaign against Scottish independence.

The former Yukos executive points out that BP's UK production has fallen from 330,000 barrels a day 10 years ago to just over 60,000 while its gas output has dwindled from 1.1 trillion cubic feet per day to 157m. In comparison BP now obtains from Russia nearly 840,000 barrels of oil a day and 800m cubic feet a day of gas.

The OGN executive believes BP's new commitment to Moscow, through becoming a 20% shareholder in state-owned Rosneft in 2012, was a dangerous move as it opens up the London-based company to reputational and financial risk.

He said: "Rosneft is not transparent. We only know from Forbes (business magazine) that Igor Sechin, the chairman of Rosneft, earned $50m last year but how much did other directors earn including (BP chief executive) Bob Dudley who is now surely a hostage to the Kremlin? I don't believe that former BP chief executives such as Lord Browne would sit on that board."

The BP spokesman said Dudley received no remuneration from Rosneft and believed the investment in Russia would offer shareholders significant long-term value and opportunities.