The Treasury is expecting a windfall running into hundreds of millions of pounds after an eBay-style auction of new nuclear power station sites is set to go into a second week.

The Government's Nuclear Decommissioning Authority launched on Monday an online auction of land next to old magnox atomic stations at Bradwell in Essex, Oldbury in Somerset and Wylfa on Anglesey.

The auction will only close after 24 hours of no bids for the lots.

That the auction is set to carry on next week is beyond the expectations of the NDA and indicates that the bidding has been hotter than thought.

The secretive bidding process is believed to have sparked at least a three-way battle between a consortium of the German power giant E.On and RWE, a grouping of GDF Suez of France, Iberdrola and Scottish and Southern Energy, and a third bidder believed to be the French giant EDF.

The Treasury has received a £4 billion windfall from the sale of its stake in nuclear generator British Energy to EDF, which has pledged to build nuclear plants at Sizewell, Suffolk and Hinkley Point, Somerset.