Britain’s parliament last night backed a second reading of legislation to sever ties with the European Union, a reprieve for Prime Minister Theresa May, who now faces demands by politicians for concessions before it becomes law.

After more than 13 hours of speeches for and against the legislation, which Mrs May says is essential for Brexit but critics describe as a Conservative government power grab, MPs voted 326 to 290 in favour of moving the EU withdrawal bill, or repeal bill, to the next stage of a lengthy lawmaking process.

Many fell in step with the government, which said a vote against the legislation would force Britain into a chaotic exit from the EU, rather than a smooth departure, as the country would lack laws and a regulatory framework to steer the process.

Mrs May, weakened by the loss of her majority in the election in June, now faces a battle against politicians who want to force amendments to the bill, first in the lower House of Parliament and then in the unelected House of Lords chamber.

"Earlier this morning parliament took a historic decision to back the will of the British people and vote for a bill which gives certainty and clarity ahead of our withdrawal from the European Union," Mrs May said in a statement.

"Although there is more to do, this decision means we can move on with negotiations with solid foundations and we continue to encourage MPs from all parts of the UK to work together in support of this vital piece of legislation."

Her justice minister urged MPs to back the bill and signalled that the government would listen to the concerns of lawmakers despite describing some of their criticism as being "exaggerated up to and beyond the point of hyperbole".

The bill seeks largely to 'copy and paste' EU law into British legislation to ensure Britain has functioning laws and the same regulatory framework as the bloc at the moment of Brexit, to offer some reassurance for companies.

But the often impassioned debate in the 650-seat parliament underlined the rifts exposed by last year's EU referendum, not only in Britain's main parties, but also in the country.

The opposition Labour Party had called on its MPs to vote against the bill if the government failed to make concessions. But seven rebelled, with some saying they had to respect the demands of their pro-Brexit voters.

"This is a deeply disappointing result," said Labour's Brexit spokesman, Keir Starmer.

"This bill is an affront to parliamentary democracy and a naked power grab by government ministers ... It will make the Brexit process more uncertain, and lead to division and chaos when we need unity and clarity."

The government has defended the bill by saying it will allow Britain to become "masters of our own laws", but it also gives ministers wide-ranging powers to amend laws to make them work domestically, often by interchanging the word 'EU' for Britain.

But MPs, both in Labour and Mrs May's Tories, expressed fears the government would make substantial changes to legislation without consulting parliament - a charge the government has denied.

Despite the victory for a government now dependent on the support of Northern Ireland's Democratic Unionist Party to secure a working majority, ministers will face attempts by both Conservative and Labour MPs to change the bill.

Some want assurances that the government will not misuse its power, others want to make sure the protections of certain workers’ rights are also written into the bill before allowing it to move to the House of Lords.

The process is expected to take months to complete and both houses should agree the final wording before it can be passed.

"Labour will seek to amend and remove the worst aspects from the bill as it passes through parliament," Mr Starmer said.

"But the flaws are so fundamental it's hard to see how this bill could ever be made fit for purpose."

EU Parliament's Brexit coordinator urges May to address chamber

Meanwhile, the European Parliament’s Brexit coordinator has said that Mrs May should address the parliament when she visits the EU legislature to clarify Britain’s plans for its divorce from the bloc.

"On Brexit, I’m very pleased that Mrs May has accepted the invitation of the European Parliament to come to the European Parliament," Guy Verhofstadt told a news conference at the parliament in Strasbourg.

Mrs May had accepted an invitation from the parliament to speak at a meeting of the heads of party groupings, he said.

"But my proposal is that instead of only addressing the conference of presidents, I would encourage her to address the full house," Mr Verhofstadt said.

He said an address by Mrs May would be very helpful because the parliament had to give its approval to a Brexit agreement between the EU and Britain, notably on the question of citizens' rights, a divorce bill and the future Ireland/Northern Ireland border.

"So in the future, all this, I think needs to be debated in an open dialogue between Mrs May and all members," Mr Verhofstadt said, adding he did not know when Mrs May planned to visit.

He pointed out that other leaders had done so in the past. They have included former US President Ronald Reagan, former French President Nicolas Sarkozy, as well as Britain's Queen Elizabeth in 1992 and two popes.

The parliament's Brexit coordinator also said that, for the moment, negotiations had not made sufficient progress on the divorce issues to allow talks to move to the issue of future trade relations between Britain and the bloc.

He added that the parliament would debate a motion in early October on whether enough progress had been made.