BORIS Johnson’s plan to increase the UK’s stockpile of nuclear warheads would breach international law, experts have warned.

The Tory government announced in March that it wants to raise the legal limit on the number of the weapons of mass destruction, which would be available to its submarine fleet at Faslane. Currently, the cap is set at 180, but the new defence review revised that up to 260.

Downing Street will also send more troops abroad “more often and for longer” as part of the £24 billion hike in defence spending.

Scotland’s Justice Secretary previously described the proposals as “utterly unacceptable", while Washington think tank, the Arms Control Association (ACA), said they were inconsistent with the UK Government’s prior pledges under the 1968 Nuclear Non-Proliferation Treaty (NPT).

READ MORE: Boris Johnson under fire for plan to stockpile more nuclear warheads

That conclusion has now been backed by two academics at the London School of Economics who were commissioned to examine Johnson’s pledge by the Campaign for Nuclear Disarmament (CND), the Record has reported.

Led by Professor Christine Chinkin, a long-time consultant for the UN, and Dr Louise Arimatsu, a former fellow at the NATO Cyber Defense Centre, the legal report finds the increase constitutes a breach of article six of the NPT treaty.

The National: The biggest and most powerful attack submarine ever built for the Royal Navy, Astute, sails up the Clyde and into the Gareloch to arrive at its home at Faslane Naval Base in Scotland for the first time. PRESS ASSOCIATION Photo. Picture date: Friday

CND general secretary Kate Hudson told the Record: "The increase in the UK’s nuclear arsenal has been exposed to intense criticism nationally and internationally, including from the United Nations. Thanks to the work of highly respected academic experts, we now know it is illegal under international law.

"Everything points to the decision costing tens of billions of pounds. During this pandemic, there are other urgent uses for public money.

"The decision breaks with the gradual nuclear reductions implemented by successive governments going back nearly 30 years and is at odds with the decision by Presidents Biden and Putin to continue bilateral nuclear reductions."

READ MORE: Boris Johnson's plan to expand nuclear arsenal ‘completely unacceptable’

Johnson announced the new vision for Britain’s global defence post-Brexit by saying the military would have to be “match-fit for the modern world”.

But a Scottish Government spokesman added: “We have stated that the UK Government’s plans to expand the stockpile of nuclear weapons, spending billions on weapons that must never be used, is a deeply disturbing response to the rapidly changing challenges of the modern age.

“Indeed the decision to increase the nuclear weapon stockpile is completely at odds with the members of the international community, who signed the United Nation’s Treaty on the Prohibition of Nuclear Weapons, a Treaty whose aims the Scottish Government supports.”

An MOD spokeswoman commented: “Maintaining the UK’s nuclear deterrent capability at a minimum credible level is fully consistent with our international legal obligations, including those under article six of the Non-Proliferation Treaty.

"The UK’s independent nuclear deterrent exists to deter the most extreme threats to the UK and our NATO allies. Our stockpile ceiling is a maximum if required, not a target nor our current number, and is kept under review.”