UK Prime Minister Gordon Brown is expected to announce to the UN Security Council that the government is willing to cut the UK’s fleet of Trident missile-carrying submarines from four to three.

The prime minister is expected to make the unilateral gesture today at a UN Security Council on nuclear disarmament and the reduction of nuclear stockpiles.

The government has however made it clear that reducing the fleet is not a precursor to abandoning the country’s nuclear programme as it views keeping the UK’s nuclear missiles as ‘non-negotiable’.

The move is also expected to provide a much-needed reduction in costs, with analysts predicting £3bn to $5bn in savings, a figure which could rise much higher if overall lifetime costs are considered.

The UK’s Trident missile-carrying fleet is made up of four ballistic missile submarines introduced in 1994 as part of the government’s nuclear weapons programme.

The submarines, one of which is on patrol at all times, are each capable of carrying 16 Trident missiles with a range of more than 4,600 miles and a destructive power estimated to be the equivalent of eight Hiroshimas.

The UK Government has already claimed to have cut down its stockpile of Trident warheads from 200 to 160.

The UN Security Council meeting will be presided over by US President Barack Obama, who is expected to lead negotiations with Moscow on the issue of Russian and American disarmament ahead of next year’s review of the Nuclear Non-Proliferation Treaty.