UK to announce plans to cut nuclear sub fleet London: Prime Minister Gordon Brown will announce Britain is prepared to scale back its nuclear capability as part of global disarmament efforts, Downing Street confirmed Wednesday. Brown will reveal Thursday at a special session of the UN Security Council plans to cut the number of planned replacement nuclear submarines from four to three, a spokeswoman confirmed. Brown will say it is time for "statesmanship not brinkmanship" on nuclear disarmament if the ambition to create a nuclear-free world is genuine, in a speech to the UN General Assembly on Wednesday. "If we are serious about the ambition of a nuclear-free world we will need statesmanship, not brinkmanship," the prime minister will say. Brown will then outline the move at the special session of the UN Security Council devoted to the issue of nuclear non-proliferation, and presided over by US President Barack Obama. The United States will also hold talks with its five counterparts -- Britain, France, Germany, China and Russia -- that have for years been negotiating with Iran on its nuclear programme. Brown will reaffirm Britain's commitment to maintaining an independent nuclear deterrent, but is prepared to reduce the number of new submarines that can launch nuclear missiles, if other countries also move on the issue. Britain's move comes ahead of next year's review of the Nuclear Non-Proliferation Treaty, which aims to limit the spread of nuclear weapons around the world, and follows a decision by Washington and Moscow to negotiate a successor to the landmark 1991 Strategic Arms Reduction Treaty (START). Brown's government has already outlined its willingness to cut nuclear arms before talks in 2010, to persuade Iran and North Korea to give up their nuclear ambitions. Britain has the fifth largest nuclear arsenal in the world, according to experts. The move on submarines could cut billions of pounds (dollars) from the defence budget over the next decade, reports said, at the same time as the government looks to cut spending to reduce public debt following a binge of spending to pull Britain out of a deep recession. Britain's Vanguard fleet is set to be replaced by the Trident nuclear weapons system at a cost of some 20 billion pounds (22 billion euros, 32 billion dollars) and is forecast to go into service in the 2020s. The Campaign for Nuclear Disarmament welcomed the move as a "serious and positive first step" towards the elimination of all nuclear weapons. Opposition Liberal Democrat leader Nick Clegg also applauded the proposal. "It's just unrealistic for us to believe that we can foot the 100 billion pound like-for-like replacement costs for Trident over the next 25 years," Clegg told the BBC. "I think the strategic context in which that decision is taking place is very different as well - we're not facing the Cold War threat in the same way that we once were."