Boris Johnson's Withdrawal Agreement Bill has been re-worked to "legally prohibit" any further extensions to the Brexit deadline.
Government sources said the Bill - due to come before the Commons on Friday - will include legislation to prevent MPs extending the Brexit transition period beyond the end of 2020.
Under current plans, Mr Johnson intends to end Britain's EU membership on January 31, with an implementation period to run to the end of 2020 while the government negotiates a free trade deal with Brussels.
However, key EU figures - including chief negotiator Michel Barnier - have expressed scepticism that a deal can be agreed in time.
A Number 10 source said: "Last week the public voted for a government that would get Brexit done and move this country forward - and that's exactly what we intend to do starting this week.
"Our manifesto made clear that we will not extend the implementation period and the new Withdrawal Agreement Bill will legally prohibit Government agreeing to any extension."
The Prime Minister repeatedly promised during the election campaign that he would not seek any extension to the transition period.
The commitment was instrumental in persuading Nigel Farage not to stand Brexit Party candidates in Conservative held seats.
The Brexit Bill could receive its first reading and be voted on at second reading on Friday, if Speaker Lindsay Hoyle agrees to the timetable.
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