A bill enacting Britain's decision to leave the European Union has become law after months of debate, the speaker of parliament announced today to cheers from Conservative Party lawmakers.

Speaker John Bercow said the EU (Withdrawal) Bill, which repeals the 1972 European Communities Act through which Britain became a member, had received royal assent from Queen Elizabeth II.

The bill transfers decades of European law onto British statute books in a bid to avoid any legal disruption.

It also enshrines Brexit day in British law as March 29, 2019 at 11pm (2300 GMT) -- midnight Brussels time, defined by the end of the two-year Article 50 withdrawal process.

The bill has undergone more than 250 hours of acrimonious debate in the Houses of Parliament since it was introduced in July 2017.

Eurosceptics celebrated the passing of the bill through parliament last week as proof that, despite all the continuing uncertainty over the negotiations with Brussels, Britain was leaving the EU.

International Trade Minister Liam Fox said it paved the way "irrevocably" for Brexit, adding that the chances of Britain not leaving "are now zero".

 Leading eurosceptic MP Jacob Rees-Mogg, a member of the ruling Conservative party, said at the weekend: "The legal position is now so much stronger for a clean Brexit.

"Crucially this makes the prime minister's negotiating hand much stronger."

Another eurosceptic Conservative MP, Dominic Raab, said May would go to an EU summit later this week "with the wind in her sails".

The government had a tough time getting the bill through parliament and was forced to concede some power to lawmakers over the final Brexit deal agreed with Brussels.