The pound could plummet to the same value as the dollar if Britain leaves the EU without a deal, British billionaire Sir Richard Branson warned on Thursday.

The Virgin boss said crashing out without agreement could leave Britain “near bankrupt,” causing big losses at his UK companies and forcing them to shift investment out of the UK.

“The pound was at $1.53 when the referendum took place. The pound today it is at $1.22, $1.23, and the pound will collapse to parity with the dollar if there is a hard Brexit,” Branson told the BBC.

"It obviously is going to result in us spending a lot less money in Britain, and just putting all our energies into other countries.”

His comments come after several days of decline for sterling against the dollar, as warning signs stack up about the poor health of the UK economy and fears grow of a hard Brexit under Boris Johnson, widely tipped to be the next UK prime minister.

READ MORE: Pound slides to two-year low as UK GDP figures revealed

Branson said all of his companies’ costs were in dollars at Virgin Atlantic. It cost around £100m a year simply to cover the same expenses when the pound plunged after the EU referendum, he said.

He warned Virgin airfreight from Europe to the US would suffer, "so that would be another £100m just down the drain."

Branson also called the UK rail franchising system a “real mess” and made it “difficult to be entrepreneurial,” as he suggested Virgin Trains may run only part of the West Coast Main Line in future after a row with officials.

A government spokesperson told the BBC other companies “clearly see an ability to be entrepreneurial” on Britain’s railways.

READ MORE: Tim Martin returns to slamming no-deal fears in Wetherspoon’s statements