The Stockholm International Peace Research Institute (Sipri) warned yesterday that the world’s nuclear weapons powers appear determined to maintain their nuclear capacity indefinitely.

Sipri said that, although there has been a steady decline in the number of nuclear warheads over the past five years, the nine nuclear weapons-capable countries still hold around 16,300 weapons.

This was down by around 5.6 per cent from last year, but the pace of reduction seemed to be slowing compared with a decade ago, the Swedish institute said.