Image copyright PA Image caption Downing Street has insisted it is still confident of a first-phase Brexit deal before next week's summit

Theresa May has been urged not to allow Eurosceptic MPs in her party to "impose their own conditions" on negotiations amid signs of fresh Tory infighting.

Nineteen Tory MPs who back a "soft Brexit" have written to her saying it is "highly irresponsible" for anyone to dictate terms which may scupper a deal.

It follows some Tories backing the DUP's decision to oppose a draft deal on the future of the Irish border.

The PM has spoken to the DUP's Arlene Foster to try to break the deadlock.

The DUP says there is "more work to be done" if it is to agree to plans for the future of the border between Northern Ireland and the Irish Republic after Brexit - a prerequisite for talks to move on to their next phase.

Irish PM Leo Varadkar, who also spoke to Mrs May on Wednesday, said he was willing to consider any new proposals, suggesting the UK might put something forward within the next 24 hours.

And the BBC understands the ambassadors of the 27 EU member states, who received an update from chief EU negotiator Michel Barnier on Wednesday, are "waiting for something from London" in the next 48 hours.

The BBC's Adam Fleming said Mr Barnier and the member states agreed there must be clarity within 48 hours for them to have enough time to consult with their capitals about draft guidelines for phase two of the talks.

At a summit next week, European leaders will decide whether enough progress has been made in the negotiations on Ireland, the UK's "divorce bill" and citizens' rights so far to open trade talks.

In their letter, the 19 MPs - who largely backed Remain in the 2016 referendum - say they support the PM's handling of the negotiations, in particular the "political and practical difficulties" relating to the Irish border.

But they hit out at what they say are attempts by some in their party to paint a no-deal scenario in which the UK failed to agree a trade agreement as "some status quo which the UK simply opts to adopt".

Media playback is unsupported on your device Media caption Citizens' rights, the Irish border and money are the three big negotiation points

"We wish to make it clear that we are disappointed yet again that some MPs and others seek to impose their own conditions on these negotiations," the MPs, including former cabinet ministers Stephen Crabb, Dominic Grieve, Anna Soubry and Nicky Morgan - write.

"In particular, it is highly irresponsible to seek to dictate terms which could lead to the UK walking away from these negotiations."

It urges the PM to "take whatever time is necessary" to get the next stage of negotiations right.

On Tuesday, former Tory leader Iain Duncan Smith argued the time was fast approaching for the UK to consider walking away from the talks if the EU did not allow negotiators to proceed to the next phase - in which future trade and security relations will take centre stage.

The suggestion of "regulatory alignment" between Northern Ireland and the European Union and any continuing role for the European Court of Justice has also concerned some Eurosceptic Conservative MPs.

On Monday Northern Ireland's Democratic Unionist Party - whose support the PM needs to win key votes at Westminster - objected to draft plans drawn up by the UK and the EU.

The DUP said the proposals, which aimed to avoid a "hard border" by aligning regulations on both sides of the border between Northern Ireland and the Republic of Ireland, were not acceptable.

This has left the UK government racing to find an agreement suiting all sides in time for next week's summit.

Image copyright PA Image caption The Irish PM said he was willing to consider any new proposals from the UK

The DUP's deputy leader Nigel Dodds said the Irish government, which has said it wants firm guarantees that a hard border can be avoided, was playing a "dangerous game" with its own economy.

At a press conference with his Dutch counterpart on Wednesday, Irish PM Leo Varadkar insisted he wanted the talks to move beyond consideration of divorce issues to the future.

"Having consulted with people in London, she (Theresa May) wants to come back to us with some text tonight or tomorrow," he said. "I expressed my willingness to consider that."

In a separate development, Chancellor Philip Hammond has suggested the UK could pay the so-called Brexit bill, regardless of whether or not there is a subsequent trade agreement with the EU.

He told MPs on the Treasury Committee he found it "inconceivable" that the UK would "walk away" from its financial obligations as "frankly it would not make us a credible partner for future international agreements".

On the issue of the divorce bill, a No 10 spokesman said the government's position remained that "nothing is agreed until everything is agreed and that applies to the financial settlement".

Reports have suggested the UK has raised its financial offer to a figure of up to 50bn euros (£44bn).