Britain's opposition Labour Party urged the government on Monday to delay signing a major rail contract as Virgin Group boss Richard Branson led a last-minute campaign to regain rights to the franchise.

Branson's Virgin Trains has run the busy London to Scotland route since 1997. But the company was outbid when rival FirstGroup, the U.K.'s largest rail operator, offered to pay 5.5 billion pounds (US$8.7 billion) for the right to run the route for the next 13 years.

The Labour Party urged the Department of Transport to put the contract on hold until lawmakers return to Parliament and have a chance to scrutinize the deal.

Branson claimed FirstGroup bid too much for the contract and would be forced to raise fares and reduce the quality of service, allegations that FirstGroup denies.

"We just want the facts examined," Branson told the BBC. "We will fight very hard to try to defend our rights to continue to operate."

An independent online petition against the decision to award the franchise to FirstGroup has gained more than 140,000 signatures from the public. Petitions to the government that gather more than 100,000 signatures may be considered for parliamentary debate, if lawmakers propose that.

Virgin Trains has offered to operate the route for a few months on a not-for-profit basis to allow extra time for lawmakers to debate the decision.

The Department of Transport said the award was decided in a "fair and established process" and that it sees no reason to delay the signing of the agreement.