British MPs and peers have backed a new law to extend the Brexit process, placing a legal requirement on Prime Minister Theresa May to seek an extension to Article 50 to prevent a no-deal Brexit.

The Commons backed a series of Lords amendments to the European Union (Withdrawal) (No 5) Act after it was rushed through both Houses of Parliament.

The cross-party move calls on Mrs May to lay a Commons motion on the extension of Article 50 which could then be amended by MPs.

The bill was amended by peers to state that nothing in it prevented the Prime Minister from "seeking or agreeing" an extension, provided it was not earlier than 22 May.

Mrs May is already seeking a further Brexit delay to 30 June and EU leaders will discuss this at an emergency summit on Wednesday.

The Commons move came as Brexit talks between the British government and Labour resumed.

But there appeared little prospect of a compromise agreement being in place in time for Wednesday's EU meeting, and no chance of it being approved by MPs before the EU27 meet.

Labour leader Jeremy Corbyn said the talks were serious, but the government was sticking to its red lines.

Mr Corbyn said: "The exchanges with the government have been serious, but our shadow cabinet expressed frustration that the Prime Minister has not yet moved off her red lines so we can reach a compromise.

"The key issues that we must see real movement on to secure an agreement are a customs union with the EU, alignment with the single market and full dynamic alignment of workers' rights, environmental protections and consumer standards.

"We are prepared to talk and put forward our view, but talks have to mean a movement and so far there has been no change in those red lines."

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The talks step-up a gear with Mrs May's defacto deputy, Cabinet Office Minister David Lidington, and Labour's shadow Brexit secretary Sir Keir Starmer taking part.

The discussions are taking place as the Tories launch a selection process for candidates to stand in European Parliament elections next month.

The government tabled an order enabling the elections to be held in Britain if the country has not left the EU by the time they are due to take place on 23 May.

The Cabinet Office said the elections would automatically be cancelled if the UK left before then.

Mrs May is to make a whistle-stop trip to Berlin and Paris for last-minute talks with Angela Merkel and Emmanuel Macron on the eve of the emergency summit.

And she spoke by phone with European Council president Donald Tusk, European Commission president Jean-Claude Juncker, Dutch PM Mark Rutte, Taoiseach Leo Varadkar and Malta's Joseph Muscat to set out the case for extending the Brexit process to June 30.

The unanimous agreement of all 27 is needed to avoid the UK leaving without a deal on Friday.

Mr Tusk has recommended a one-year extension to the Brexit process, with a break clause allowing an earlier departure if a withdrawal deal is ratified in Westminster.

Speaking during a visit to Dublin, the EU's chief Brexit negotiator Michel Barnier said the UK could not escape demands for a £39 billion payment and a backstop for the Irish border by quitting without a deal.

The Prime Minister has angered Tories by holding talks with Labour, with Brexiteers including Boris Johnson concerned that she will accept a customs union as the price for a deal with Mr Corbyn.

In a bid to end the deadlock with Labour, the Prime Minister is considering offering MPs a vote on whether to hold a referendum on any deal agreed between on Brexit, according to the Daily Telegraph.

Let me explain what's happening with Brexit.pic.twitter.com/gjGkvFk8fT — Theresa May (@theresa_may) April 7, 2019

In a video message recorded in her Chequers country retreat at the weekend, Mrs May said both sides in the cross-party talks will have to compromise.

The Prime Minister acknowledged she could not see the Commons accepting her deal in its current form and MPs would not agree to a no-deal exit.

Prominent Brexiteer, Mark Francois, called for an "indicative vote" among Tory MPs on the PM's future on Wednesday to send a signal to the Brussels summit that Mrs May has lost the confidence of her own side and cannot deliver a Brexit deal.

But it is understood that the executive of the backbench 1922 Committee considered this option last week and decided it was not appropriate at this stage. A formal confidence vote cannot take place until December.

Additional reporting: PA