Theresa May took a swipe at Boris Johnson from the conference stage and mocked his foul-mouthed attack on business.

The former foreign secretary caused anger in the corporate world earlier this year when he dismissed concerns over Brexit and reportedly said “f*** business”.

Mocking Mr Johnson, whose leadership ambitions have again dominated the annual autumn Tory gathering, the Prime Minister insisted the Tory party is firmly behind business.

She told activists: “To all businesses, large and small, you may have heard that there is a four-letter word to describe what we Conservatives want to do to you.

“It has a single syllable. It is of Anglo-Saxon derivation. It ends in the letter k.

“Back business. Back them to create jobs and build prosperity. Back them to drive innovation and improve lives.

“Back them with the lowest corporation tax in the G20.

“Britain, under my Conservative government is open for business.”

Mr Johnson addressed a rapturous crowd of 1,500 conference-goers on the fringes on Tuesday in a move that was widely seen as an attempt to undermine the Prime Minister and set out his leadership pitch.

Ahead of Mrs May’s speech, one of the former Cabinet minister’s allies criticised the premier and called for a no-confidence vote.

James Duddridge, a former minister, submitted a letter to the backbench Tory 1922 Committee, saying: “I have not met a single MP who thinks she will lead us into another election.”