Theresa May has been accused of “running scared” of a Commons vote on whether the UK should stay in the EU customs union, after the clash was shelved.

The showdown on one of the key Brexit disputes has been delayed until at least April, The Independent has learned, as the Government contemplates a possible defeat.

The Prime Minister is believed to be determined not to risk such a show of weakness until after next month’s crucial European Council meeting, which is meant to agree the transitional deal she is seeking.

Chris Leslie MP, a Labour MP backing the amendment, said: “It looks like the Government is running scared from a vote on the customs union, because they're terrified they'll lose.

“MPs from across all parties have the national interest at heart in wanting to ensure we don't crash out of the customs union, damaging trade with our largest partner and putting jobs in this country at risk.”

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Anna Soubry and Ken Clarke, two prominent pro-EU Conservative MPs, are leading a Tory rebellion to keep Britain “in a customs union in the EU in the same terms as existed before exit day”.

Labour is likely to vote for the amendment, after Jeremy Corbyn said, this week: “We have to have a customs union.”

The new Commons timetable confirms that a vote – expected next week – has been delayed until at least next month, but The Independent has been told it will not be staged until after Easter.

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Mr Leslie, a supporter of pro-EU Open Britain campaign, said the Prime Minister could not avoid the clash, adding: “Parliament will have its say on this, whether the Government wants it to or not.”

Ms Soubry and Mr Clarke have tabled similar amendments to both the Taxation (Cross-Border Trade) Bill and to the separate Trade Bill.

The amendment to the Trade Bill is easier for Labour to support because it would keep the UK in “a customs union in the EU” – rather than “the customs union”.

John McDonnell, the Shadow Chancellor, said the party could support “a customs union” because it would give the UK the ability to “influence trade negotiations”, instead of tying its hands.

Separately, furious pro-Brexit Tories are poised to mount a stand because the Taxation Bill would allow for Britain to rejoin the EU customs union without a further Bill, should MPs vote for it in future.

Ms May has vowed the UK will leave the single market and the customs union, but conceded she must abide by their rules in the transition period of “around two years”.

Businesses have repeatedly warned of their fears that leaving will bring an explosion in red tape, disruption to trade flows and huge queues at border points.

Meanwhile, the EU believes that only staying in both the single market and the customs union can solve the problem of avoiding new border post and checks on the Irish border.