MPS will be challenged by Theresa May in the House of Commons today to explicitly back her to trigger Brexit by March 31 next year, a Tory MP has revealed.

Hours after that revelation, the BBC reported that Number 10 has accepted Labour’s attempt to force the Prime Minister to publish a plan for Brexit before Article 50 is triggered. May will hope the moves fend off a potential Commons rebellion as up to 40 Tory backbenchers were thought to be ready to back Labour’s motion to be debated today, which calls for her to set out her Brexit plan.

An amendment in the name of the Prime Minister will accept the Labour motion, allowing potentially rebellious Tories to back it, prominent Eurosceptic Steve Baker revealed yesterday.

But it will also challenge them to “respect the wishes” of voters in the referendum and call on the Government to trigger Article 50 by the end of March – in accordance with the timetable set out by the PM.

Meanwhile, the SNP has tabled an amendment calling for a formal role for devolved nations in the EU negotiations and for the UK Government to seek agreement from devolved administrations before triggering Article 50. The party urged Labour to support the amendment or risk backing a “damaging” hard-right Tory Brexit.

Government sources told the BBC that May has agreed to publish her Brexit “plan” in exchange for Labour’s commitment to Article 50 being triggered before the end of March. The sources would not give details on the extent of the plan nor give a timetable for implementing it.

A Downing Street spokesman stressed that the amendment was “a separate issue” from the Government’s Supreme Court battle to overturn a ruling that it should obtain Parliament’s approval before triggering Article 50.

May’s move also allows Tories to back Labour’s motion, which acknowledges that some elements of the negotiating position should remain secret but urges the Prime Minister to “commit to publishing the Government’s plan for leaving the EU” before triggering Article 50. Explaining the thinking behind the Government amendment, a Downing Street source said: “Crucially, from our perspective, it’s making sure that Parliament is very clear it is not going to use this as a delaying method.”

As news of the Government amendment emerged, Tory MP Anna Soubry, one of the potential rebels, claimed the Scottish Parliament is entitled to “a legislative consent motion on Article 50”, and stressed the biggest challenges facing the UK Government is the arguments in the Supreme Court around the devolved administrations.

SNP MP Stephen Gethins MP, the party’s Europe spokesman said the debate is welcome in holding the UK government to account for being “shamefully silent”, but flawed for failing to acknowledge and respect the will and vote of people in both Scotland and Northern Ireland.

Gethins said: “For almost six months the UK Government has been shamefully silent on its preparations for negotiations with the European Union, despite livelihoods and businesses relying so heavily on the UK’s relationship with the EU. This vacuum has resulted in absolute chaos at the heart of Downing Street, and the Supreme Court case goes one step further to show that rather than focusing on the impact leaving the EU will have, the UK Government is willing to put jobs and the economy at risk by their continued inaction.

“While we welcome the debate and agree that the UK Government needs to be held to account, the SNP has put forward an amendment to the Labour motion that will respect parts of the UK, like Scotland, who voted overwhelmingly to remain in the EU, and will call for a formal role for the devolved administrations including seeking their agreement before Article 50 is triggered.

“This amendment seeks to give representation and a say to the devolved administrations across the UK and ensure that Westminster understands that the SNP will do all it can to protect Scotland’s interests.

The Liberal Democrats said May must now set out whether she plans to keep the UK in the European single market. Foreign affairs spokesman Tom Brake said: “Five months on, finally this Conservative Brexit Government is admitting that triggering Article 50 without a plan would be like jumping out of a plane without a parachute.”