Downing Street has breached a “clear promise” by Boris Johnson’s government to give MPs a vote on extending the post-Brexit transition period to avoid no-deal, a former Tory cabinet minister has said.

The prime minister’s official spokesman answered “a simple no” when asked on Tuesday if MPs would get a vote on prolonging the transition.

He insisted there would be no need for an extension because the UK and the EU would have agreed a free trade deal by December 2020, in an attempt to reassure Brexiteer Tories.

But ex-justice secretary David Gauke said this breaks a commitment made in the Commons by Justice Secretary Robert Buckland that the government would “abide by” MPs’ vote on the issue.

Under the terms of that deal, Britain would continue to follow EU rules after it has left the bloc until the end of 2020 to allow time for the two sides to reach a long-term free trade deal.

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Gauke is among many MPs concerned that it would be difficult to complete the negotiations to such a tight timetable, and that it risked opening a second “trapdoor” to a no-deal Brexit if the UK and EU were unable to reach an agreement in time.

He backed the PM’s Brexit deal and the timetable for passing it through parliament, which ultimately failed, after Buckland made his commitment.

Responding to No.10’s comments, Gauke said: “It was a clear promise. 

“As Robert Buckland said ‘parliament has a legitimate role to play’. I agree.

“Looks like the Conservative message is ‘we’ll be out on WTO (no deal) terms by 2021’. 

“I have to say – that is reckless.”

Another former Tory, Nick Boles, claimed Johnson withdrew his Brexit deal and plumped for a general election because he knew MPs would pass an amendment to ensure they got a vote on extending the transition.

“One of the main reasons (Dominic) Cummings refused to allow the Brexit bill to go through parliament was that the Commons would have passed my amendment to make an extension to the transition the default unless MPs decided otherwise. 

“Johnson wants to force through a WTO Brexit next December,” he said.

Pressed on Tuesday whether MPs would be given a vote on a possible extension, Johnson’s spokesman said: “The answer to that is a simple no.

“We aren’t extending the implementation period. There is no reason whatsoever why we will not secure a deal by that date.

“Both the UK and the EU are committed to reaching a trade agreement by that date and that is what we are going to do.”