The international nuclear watchdog is to carry out a security inspection at the Sellafield reprocessing plant as part of a worldwide drive to stop the spread of fissile materials, Gordon Brown announced today.
The Prime Minister said that Britain is also launching a "centre of nuclear excellence" where the UK could "lead global efforts to secure the safe global expansion of civil nuclear power".
Speaking to the Foreign Press Association in London, Mr Brown said it is essential to prevent nuclear weapons falling into the hands of rogue states and international terrorists.
He said that Britain is joining US President Barack Obama's drive to secure all fissile nuclear material across the world over the next four years.
"In line with this we will invite the International Atomic Energy Authority to carry out a security inspection at Sellafield. We will make funds available for similar inspections in areas of greatest concern," he said.
Mr Brown said that he had struck an agreement on further nuclear co-operation with France in talks last week with President Nicolas Sarkozy, but stressed that both countries would retain their own independent deterrents.
"We have agreed a degree of co-operation that is, I think, greater than we have had previously but we will retain, as will France, our independent nuclear deterrent," he said.
"We wish, of course, to see multilateral disarmament around the world and we are ready to contribute towards that, but in a world that is so insecure, particularly with other countries trying to acquire nuclear weapons, we do not see the case for us withdrawing the independent nuclear deterrent that we have."
The Prime Minister also called for fresh international measures against countries like Iran which were trying to acquire nuclear weapons.
"Countries like Iran who try secretly to develop nuclear weapons must face concerted and decisive action by the international community including more far-reaching international sanctions," he said.