"This is an extraordinarily complex and critical project. And there is an acknowledgment that the existing budget will not be enough to deliver it, given the inflationary pressures we're seeing. This extra funding will allow us to progress on schedule without having to raid other parts of the budget," a senior Whitehall source was quoted as saying by the newspaper.
Part of the funding will be spent on replacing outdated nuclear submarines with Dreadnought-class submarines, the report said.
Sunak will hold meetings with US President Joe Biden and Australian Prime Minister Anthony Albanese next week to confirm the defense funding before UK Chancellor of the Exchequer Jeremy Hunt publishes his state budget, the report also said.
It added that the leaders would also announce a new agreement allowing Australia to buy UK Astute class nuclear-powered submarines under the AUKUS pact.