Concerns by the French nuclear safety watchdog over the energy giant EDF’s new nuclear power plant in France has fuelled opposition to the firm’s plans in Somerset.

EDF is building a new “European Pressurised Water Reactor” at Flamanville in France. Its proposed new nuclear power plant at Hinkley will have two of the same reactors.

However, the French nuclear safety authority, ASN, has told EDF to fix a series of “gaps and weaknesses” in its construction.

In a 20-page report revealed in the French press, ASN highlights a number of deviations from construction requirements affecting essential parts of the reactor, including the steam generators, water injection filters and batteries used for the cooling system.

On the steam generators, the report says that “the quality of materials, taking into account their importance for safety, has not been demonstrated and their use (at Flamanville) is not possible”.

EDF recently received approval from West Somerset Council to carry out preparatory work at Hinkley, including initial excavation of the reactor foundations. It is due to submit a planning application to the Infrastructure Planning Commission later this year.

The Financial Times has claimed the Flamanville plant is now expected to cost £6 billion euros, compared to the £3.3 billion it was originally said to cost, and will not to be ready for operation until 2016, four years late.

Crispin Aubrey, spokesman for campaign group Stop Hinkley said yesterday (Tuesday): “These reports cast further doubt on the integrity of the French reactor design, and, given the continued increase in costs, whether it will be economical to build in this country. This provides yet another reason why EDF should not be allowed to carry out any preparatory work at the site before it gets the go-ahead for the power station itself from the appropriate authorities.”

A spokesman for EDF said: “As would rightly be expected, the Flamanville EPR construction site is stringently controlled by the French nuclear safety authority.

“There is regular interaction between ASN and EDF, including an examination every two weeks of EDF's nuclear power plants by the safety authority.

“EDF has answered several key points in response to ASN's letter of July 22, notably regarding the RIS accumulator. EDF has subsequently provided additional information expected by the ASN.

“The planning for the Flamanville EPR remains unchanged and there will not be any additional delay.

“The experience at Flamanville is invaluable as we progress in the UK. Each time EDF builds the EPR, our expertise increases. We are already seeing the benefits of the experience from existing projects. We are making good progress in the UK. We are in the final stages of licensing the EPR. It is a good design which the UK regulator said last month is capable of being accepted.” We remain committed to the UK and to our new nuclear programme.”