Gazprom, the Kremlin-backed Russian gas group, is negotiating a deal under which it could take a stake in up to five British gas-fired power stations. The move would be Gazprom’s biggest step in the UK market so far and would fuel fears about the security of future energy supplies.

Gazprom is hoping to seal an asset swap with E.ON, its German rival, which owns Powergen and has about 10 per cent of electricity sales in the UK.

Under the deal E.ON would take a 25 per cent stake in the huge Yuzhno Russkoye gasfield run by Gazprom. The Russian field is expected to be the main source of gas for the new Nord Stream continental pipeline. In exchange, Gazprom wants a stake in E.ON’s UK power stations. E.ON is also understood to have offered Gazprom a share of its gas and power operations in Hungary. Gazprom is believed to want more, given the value of the Yuzhno Russkoye project.

Gazprom has made little secret of its desire to break into the UK power market and has continually been linked with a possible takeover of Centrica, the owner of British Gas.

British politicians would face calls to resist a deal, given the pressure from Russian regulators that has forced both BP and Shell to cede control of key projects in Russia in the past year.