Nations with huge nuclear arsenals are wasting their money because just 100 missiles would be enough to destabilise the globe and kill their own citizens, scientists have said.

Britain currently possesses approximately 215 warheads of around 15,000 worldwide, the vast majority of which are American or Russian.

But researchers have determined that no nation could fire more than 100 without causing a chain of events so catastrophic the impacts are felt at home.

In the first such exercise of its kind, scientists analysed the “environmental blow-back” of a one-way but massive nuclear strike.

Based on models including those of burnable materials in cities, they calculated the amount of soot and dust that would be thrown into the air by the blasts, the consequent blotting of the sun and damage to the atmosphere.