UK PM pledges post-COVID spending boost

British Prime Minister Boris Johnson has promised a "Rooseveltian" boost to public spending to help the country's economy recover from the coronavirus shock and says a return to austerity would be a mistake.

Johnson said he would double down on his plans to increase investment and said his government - which has already announced emergency spending and tax measures worth an estimated STG133 billion ($A239 billion) - would continue to help people and businesses.

"This is the moment for a Rooseveltian approach to the UK," Johnson told Times Radio on Monday.

Former US President Franklin D. Roosevelt's "New Deal" program, which included a raft of job-creating public works projects, helped the United States recover from the Great Depression.

"I do think the investment will pay off because this is a very, very dynamic, very productive economy," Johnson said, promising a platform that would encourage companies to invest in capital and in skills training.

Earlier on Monday, Britain's debt office said it plans to sell a record STG275 billion of government debt between April and August to pay for the huge spending response to the coronavirus pandemic, more than double the amount sold in the whole previous financial year.