France offers to join forces with UK’s nuclear submarine fleet

Officials from both countries have discussed a deterrent-sharing scheme but Britain has so far opposed the idea

France has offered to create a joint UK-French nuclear deterrent by sharing submarine patrols, the Guardian has learned.

Officials from both countries have discussed how a deterrence-sharing scheme might work but Britain has so far opposed the idea on the grounds that such pooling of sovereignty would be politically unacceptable.

In a speech this morning in London, Gordon Brown said he had agreed to further nuclear co-operation with France last week after talks with Nicolas Sarkozy. The prime minister did not comment explicitly about submarines, saying only that the UK and France would both retain “our independent nuclear deterrent”.

Britain and France each maintain “continuous at-sea deterrence”, which involves running at least one nuclear-armed submarine submerged and undetected at any given time. It is a hugely expensive undertaking, and its usefulness in a post-cold war world has long been questioned by disarmament campaigners.

Britain’s independent deterrent, based on Trident missiles carried by submarines, could cost the country up to