Gordon Brown is considering a cut in the number of warheads in the UK’s nuclear arsenal by 25 per cent early next year in a move aimed at underscoring Britain’s commitment to international disarmament.

As Britain prepares for two disarmament summits next year ahead of the general election, a reduction in the number of the “operationally available” warheads from 160 to about 120 is being investigated by Downing Street.