Theresa May has been accused of trying to “railroad” a hard Brexit through Parliament after it emerged she will give MPs one half-day to discuss and vote on the EU Withdrawal Bill.

Downing Street confirmed that the Commons would have 12 hours to consider all 15 amendments that were added to her flagship legislation following a string of defeats in the House of Lords.

The highly unusual decision to cram the bill into one day on Tuesday, June 12, prompted a backlash from critics who claimed the Prime Minister was scared of ‘Remain’ Tory backbenchers allying with Labour.

The 12-hour timetable would see MPs voting as late as 3am, as Government whips try to wear out their opponents.

HuffPost has learned that Shadow Chief Whip Nick Brown is threatening ‘reprisals’ if the Government refuse to grant a three-day timetable, possibly even breaking off all “usual channels” that allow Parliament to function.

Speaking to the weekly Parliamentary Labour Party (PLP) meeting, a furious Brown questioned whether it would even be ‘safe’ to have 650 MPs trying to get home in the early hours without public transport.

The PM’s official spokesman said that the EU Withdrawal Bill would return to the Commons next week and it was set to be heard in “one day”.

The move follows a series of major Government defeats as peers sought to get a ‘soft Brexit’ by including plans to stay in a customs union and single market with the EU.

Shadow Brexit minister Jenny Chapman said: “Ministers have spent months delaying Brexit votes in Parliament because they fear defeat.

“Now they want to railroad through crucial legislation and limit the chance for proper debate and scrutiny. 

“Theresa May should stop treating Parliament with such contempt and rethink these proposals as a matter of urgency.”

Asked by HuffPost for the Government’s response to accusations of railroading the bill through, the PM’s spokesman replied: “We’ve made clear all along there will be time for debate on this topic.

“It’s obviously been debated at length in the House of Lords and the House of Commons already.”

But Lib Dem MP Layla Moran, of the pro-EU Best for Britain campaign, said: “The Government are trying to rig Parliament over these Brexit amendments and we won’t have it.

“It is not trying to win the argument but grind MPs down. It’s petty politics because the Government are losing their debate.”

Labour’s Chuka Umunna said the plan proved why the People’s Vote campaign was right to demand a new referendum on the final deal.

“It is absolutely outrageous for the Government to allocate just one day to a debate that promises to be crucial for the future of our country.

“But it is unfortunately in keeping with their whole approach to Brexit: shambolic, lacking transparency or accountability and contemptuous of basic parliamentary scrutiny.

“People will not be fooled. I hope MPs will vote in favour of the vital amendments to this Bill, in particular those that seek to keep the UK in the Customs Union and in Europe’s economic area.”

A letter to Tory MPs from Chief Whip Julian Smith, leaked to the Times, showed how seriously ministers viewed the knife-edge votes coming up.

The Government has delayed bringing the EU Withdrawal Bill back to the Commons in order to build as much support as possible, while whittling down the number of possible Tory rebels.

Labour will be hoping some ‘constitutional Tories’ could help them block a programme motion setting out the 12-hour timetable.

A spokesman for Labour’s whips office said: “This is an absolute disgrace if true. Must be out of sheer panic.

“The House of Commons has had nothing to do for months in terms of substantive business and to try to ram through in one day shows the contempt that the Government have for the role of Parliament.”

Stephen Gethins, the SNP’s foreign affairs spokesman, added: “The Tory Brexit bill threatens to grab powers from the Scottish Parliament, and deals with huge issues including whether MPs get a meaningful vote on the final Brexit deal, whether or not we leave the single market and customs union, our human rights, environmental protections, and the situation in Northern Ireland

“It is disgraceful and anti-democratic that it is now attempting to rush it through Parliament, without a full debate, in order to overturn important amendments.”