Theresa May is attempting to prevent a Tory rebellion over Brexit ahead of the first Commons votes on the legislation to withdraw from the European Union.
The Prime Minister’s allies have warned would-be rebels that they risk putting Jeremy Corbyn into Number 10 if they attempt to water down the so-called Repeal Bill.
Ms May said the legislation – officially called the European Union (Withdrawal) Bill – would give legal certainty to people and businesses and insisted there would be “proper Parliamentary scrutiny”.
But pro-EU Tories claimed the whipping operation to ensure they backed the legislation could backfire and potentially damage Ms May’s already weakened leadership.
The legislation will be debated on Thursday after MPs return to Westminster following a summer break in which some have been plotting their tactics for the Brexit battles ahead.
Ms May said: “Since Parliament broke for summer the Government has been working hard to deliver a successful Brexit.
“The series of papers we are publishing have provided further detail on the deep and special partnership we want, we’ve had frank negotiations with the Commission, and we’ve travelled the globe to establish the trading relationships of the future.
“Now it is time for Parliament to play its part. The Repeal Bill delivers the result of the referendum by ending the direct role of the EU in UK law, but it is also the single most important step we can take to prevent a cliff-edge for people and businesses, because it transfers laws and provides legal continuity.
“We have made time for proper Parliamentary scrutiny of Brexit legislation and welcome the contributions of MPs from across the House.
“But for us to grasp the great prize ahead of us, that contribution must fit with our shared aim: to help Britain make a success of Brexit and become that great global country we know we can be.”
Her de facto deputy Damian Green, the First Secretary of State, used a Sunday Telegraph article to warn Tories not to derail the legislation.
“Starting the new parliamentary session with the Withdrawal Bill shows that it is now the job of all MPs, including my former colleagues on the Stronger In campaign, to respect the will of the people and get the best possible deal for Britain,” he said.
“No Conservative wants a bad Brexit deal, or to do anything that increases the threat of a Corbyn government.”
But the outspoken pro-Remainer and former minister, Anna Soubry, responded angrily to attempts to try to stop Tory MPs tabling or supporting amendments to the legislation, telling the Observer: “Any suggestion that this is in any way treacherous or supporting Jeremy Corbyn is outrageous.
“It amounts to a trouncing of democracy and people will not accept it.”
She added: “People will be very alarmed. It will all backfire on them.”
Meanwhile Number 10 sources rejected as “not true” a Sunday Times report that Ms May was preparing to approve a Brexit divorce bill of up to £50bn after the Tory conference in October.
The financial settlement was the subject of a bitter row between Brexit Secretary David Davis and Brussels’ chief negotiator Michel Barnier during the latest round of negotiations.
The newspaper said under plans being drawn up in Whitehall the UK would pay between £7bn and £17bn a year to Brussels for three years after Brexit – with the final bill set to be up to £20bn higher than hoped, as a result of the Prime Minister’s weakened domestic position since the general election.