Russia has begun mass-producing mobile bomb shelters that can protect against shockwaves and radiation from a nuclear blast.

The new 'KUB-M' shelters will offer protection for 54 people for up to two days against natural and man-made hazards, Moscow's emergency ministry has said.

It comes as Vladimir Putin this morning signed off a document to lower Russia's threshold for launching nuclear weapons.

The new doctrine, which replaces the previous iteration outlined in 2020, allows Moscow to deploy its weapons if Russia or Belarus is threatened by a non-nuclear nation supported by a nuclear power. 

The 'KUB-M' mobile bomb shelters look like reinforced shipping containers and consist of two modules - a room for 54 people and a technical block. 

'The mobile shelter is a multifunctional structure that provides protection for people from various threats, including natural disasters and man-made accidents,' the research institute said, calling it 'an important step towards improving the safety of citizens'.

They can easily be transported on a truck and connected to water supplies, and can also be deployed in Russia's vast northern permafrost, it added.

The move has not been linked to any current crisis, although the announcement came just days after President Joe Biden agreed to allow Ukraine to fire US long-range missiles deep into Russia.

The Kremlin has branded this decision as reckless and warned that it would draw a response from Moscow. 

Prime Minister Sir Keir Starmer also today gave his strongest signal yet that Ukraine would be allowed to fire UK-made ballistic missiles into Russia. 

When asked at the G20 summit in Brazil whether Kyiv would be able to use the weapons, he said: 'I've been doubling down in my clear message that we need to ensure Ukraine has what is needed for as long as needed to win this war against Putin.

'I am not going to go into operational details. You would not expect me to. The only winner in that would be Putin and it would undermine Ukraine.'

Zelensky has previously asked for Britain to give him permission to use its Storm Shadow missiles on targets in Russia - a plea which has so far been rebuffed by Downing Street.