Gordon Brown will signal his readiness to scale back Britain's Trident nuclear deterrent as part of an international deal to dramatically cut the world's nuclear arsenal.
The Prime Minister is expected to tell world leaders meeting this week at the United Nations in New York that he is prepared to consider cutting the UK's fleet of Trident missile-carrying submarines from four to three.
His offer comes as US President Barack Obama is pressing ahead with ambitious plans for international talks to halt the spread of nuclear weapons and reduce existing stockpiles.
In his address to the UN General Assembly, Mr Brown will call for all nations to come together to achieve the long-term ambition of a nuclear-free world.
"If we are serious about the ambition of a nuclear-free world we will need statesmanship, not brinkmanship," he will say, according to an advance extract from his speech.
He will then spell out the details of his offer at a special session of the UN Security Council, summoned by Mr Obama, on disarmament and non-proliferation.
It will cover the planned £20 billion Trident modernisation programme - with the four existing submarines being replaced by just three boats.
Critics will argue that the reduction will make little difference to the UK's overall capability and may well have happened anyway as ministers search for cuts to reduce the massive deficit in the public finances.
The Government has already announced that it has cut the UK's stockpile of Trident warheads from 200 to 160, and many Labour MPs would like the Government to scrap the deterrent altogether.
Read More
Officials travelling with the Prime Minister insisted the maintenance of the UK's independent deterrent remained "non-negotiable".
