EDF, the state-controlled French utility, made a takeover offer yesterday for British Energy, the UK's nuclear power provider.

Neither British Energy nor EDF, which was last night believed to be putting the final touches to an alliance with Centrica, the owner of British Gas and Scottish Gas, would disclose how much money was put on the table.

However, City analysts said they believed EDF had offered much less than 700p a share, because of technical problems with British Energy's ageing fleet of nuclear stations.

British Energy shares had been trading recently at around 715p and some industry sources have said the company could be worth more than 800p a share.

"The bidding companies have talked the price down quite successfully," said Simon Edrich, an analyst at the London office of the Dutch bank ING.

British Energy shares shed 14p to 701p by the close of London dealing amid speculation that the EDF offer may be below the key 700p level.

The UK group's shares have risen almost 40% since it emerged in March that the power generator's board was considering a break-up or a sale. British Energy stipulated that all bids for the company had to be tabled by yesterday afternoon. Industry sources said no other offers have been made, but counter-bids in the near future would still be considered.

Centrica was believed to be close to a deal with EDF, Europe's biggest power company, to set up a joint venture vehicle to run British Energy. Sources said the French company will hold 75% of the joint venture and Centrica will have the other 25%.

Several companies other than EDF had shown an interest in bidding for British Energy, including German-based RWE and Spain's Iberdrola, the owner of ScottishPower, but got cold feet at the last moment.

In a sign of EDF's determination to begin developing nuclear power stations in Britain, it is understood to have bought land in Somerset and Anglesey, next to existing power stations at Wylfa and Hinkley Point, which is large enough to provide space for one of its European pressurised reactors.

Wylfa, on the island of Anglesey, is owned by the Nuclear Decommissioning Authority and has already attracted interest for a potential new reactor from other energy groups. Hinkley Point, in the south-west of England, is owned by the NDA and British Energy.

British Energy has eight nuclear power stations generating about 20% of the UK's electricity needs, and is attractive to bidders because the government has given the green light for the building of a new generation of nuclear power plants, and British Energy's sites are considered prime locations for the developments.

The government has a 35% stake in British Energy and has indicated that it is prepared to sell at the right price regardless of the nationality of the bidder.

EDF is 84%-owned by the French government. It operates nearly 60 nuclear power stations in France and has already submitted for regulatory approval the design of the plants it wants to build in Britain. If EDF is successful in its bid for British Energy, it will play a big role in financing and developing a new generation of nuclear power stations, which the government considers essential for the UK's energy security.