Government sources said welfare would be spared from a 'Cabinet whip-round' designed to raise money for the UK's cash-strapped armed forces.

Downing Street had hoped to publish the Defence Investment Plan this week, amid dire warnings about Britain's ability to defend itself from Russia and other foes.

Government sources said welfare would be spared from a 'Cabinet whip-round' designed to raise money for the UK's cash-strapped armed forces.

Rachel Reeves gave the grim signal as frantic wrangling continues in Whitehall over how to pay for bolstering the country's military.

The Treasury is understood to have cut £5 billion from an increase in Armed Forces investment to meet the threat posed by Russia.