Jeremy Corbyn will order Labour MPs to back a vote on triggering Article 50, the mechanism to split from Brussels, the left-wing leader suggested on Thursday (19 January).
The development comes amid reports that some shadow cabinet ministers were considering voting against invoking Article 50.
"I've made it very clear the Labour Party accepts and respects the decision of the British people. We will not block article 50," he told Sky News.
When pressed on whether that meant he would impose a three-line-whip, Corbyn said: "Labour MPs will be asked to vote in that direction next week, or whenever the vote comes up."
The Labour leader's office refused to comment on whipping matters when approached by IBTimes UK.
But Corbyn could face a backlash if he calls for a three-line-whip, which typically instructs MPs to attend the House of Commons and vote on a specific bill.
The Labour leader was the most rebellious MP during New Labour's reign in government between 1997 and 2010.
University of London's Professor Philip Cowley, an expert on parliamentary revolts, noted in 2015: "Over those 13 years in government, he defied the whip 428 times. In the last five years, he dropped into second place but only just, one vote behind [Shadow Chancellor] John McDonnell."
The Supreme Court will decide on Tuesday whether MPs and peers should have a vote on invoking Article 50.
The historic judgement comes after an appeal by the government, who unsuccessfully argued at the High Court that ministers had the legal authority to trigger the mechanism without consulting parliament.
- Government will provide certainty and clarity to politicians and businesses.
- UK will 'control our own laws' by quitting the European Court of Justice.
- May will strengthen the 'precious union' between England, Wales, Northern Ireland and Scotland.
- There will be no hard border between Northern Ireland and the Republic of Ireland.
- UK will 'control' EU immigration, while recruiting the 'brightest and the best' from around the world.
- Government will seek a reciprocal residency rights deal for EU and UK workers 'as soon as possible'.
- May has promised to protect workers' rights.
- Ministers will seek a 'bold' and 'comprehensive' free trade agreement with the EU.
- UK will seek a customs agreement so that it can broker its own trade deals with non-EU nations.
- May will keep European science and innovation ties in bid to keep the UK a 'world leader'.
- UK will continue to work with the EU in bid a bid to combat the threat of terrorism.
- Ministers will seek to avoid a 'cliff edge' and seek a smooth split from the EU.
Theresa May has promised to invoke Article 50 by the end of March. The move will start a two-year-long negotiation process with the EU.
The prime minister outlined her 12-point Brexit plan to diplomats and politicians at Lancaster House, London, on Tuesday.
May revealed that the government will not seek to maintain the UK's membership of the EU's single-market.
Green co-leader Caroline Lucas claimed May's stance was "reckless" and urged Corbyn not to whip his MPs.
"Yanking the UK out of the single market is reckless and the Prime Minister is taking an extreme gamble with our future," she said.
"Jeremy Corbyn is now trying to deny Labour MPs the chance to make their own principled choice on one of the most important decisions of the UK's recent history.
"This isn't about ignoring the result of the referendum, it's about May interpreting a slim majority in favour of leaving as a mandate to sacrifice our economy on the altar of ending free movement.
"It's astonishing that Labour are willing to effectively grant the Government that mandate rather than making the case for a future in which the benefits of a close relationship with the EU are more fairly and equally shared."