More then 1,700 nuclear missile warheads in the British arsenal have a design flaw and could set off a chain reaction 'like popcorn' if dropped, reveal Ministry of Defence documents, according to the Telegraph newspaper.

A nuclear warhead is designed to be ‘singlepoint safe’ which means it will not be triggered accidentally by a single sudden hit.

However, an MoD safety manual declassified last month argued this was not enough, and if a warhead were subject to numerous simultaneous impacts it could still 'popcorn'.

The document also recommends replacing the sensitive explosives surrounding the plutonium core. Less sensitive explosives would be bulkier and weigh more, but they would not detonate accidentally. This would require the redesign of warheads, reports The Telegraph newspaper.

A single nuclear missile like submarine-based Tridents can contain several warheads, and some subs carry up to 24 missiles. If one warhead goes off, it could trigger all others in a chain reaction called ‘popcorning’.

U.S. and British military officials argue such an accident is unlikely and would require serious violation of nuclear weapons handling procedures.

Some military experts pointed out safety regulations do get violated by the military, citing the resent case when a U.S. Air Force bomber was accidentally loaded with nuclear weapons and then travelled across the country.

They also say emergency scenarios – for example if a warhead is hit by several direct gunshots – could still pose a great risk of explosion.