Theresa May has come under pressure from Tory bankbenchers over claims she privately agreed to pay the EU a bigger divorce bill to speed up the Brexit talks.

The Prime Minister was told not to hand over “a penny more” than Britain owes, with one backbencher suggesting it would be impossible to “look public sector workers in the eye”.

The warnings, during a Commons statement, laid bare the difficulty Ms May faces in meeting the EU’s demand to up her offer in order to break the deadlock in the negotiations.

Without a concession on the financial settlement, the EU will not agree to discuss future trade or a transition deal – provoking mounting alarm among business leaders.

It has been claimed that Ms May said Britain was prepared to pay future liabilities of up to €20bn (£17.7bn) to secure a two-year transition – on top of promised “subs” of €20bn.

In the chamber, Edward Leigh, a senior Tory backbencher, demanded openness, telling the Prime Minister: “We still have no idea what we have offered, what they are demanding.”

He warned: “I think we could do with some more information, because ultimately there will be a vote on this in this House – and that will be a vote that counts.”

John Whittingdale, the former Culture Secretary, insisted she only budge from the initial €20bn pledged if the EU shows “flexibility” on future trade.

And another backbencher, Philip Davies, said that any “spare tens of billions” should be spent on “social care and pay rises for public sector workers”.

The Tories would not be able to “look public sector workers in the eye” if money went into the “bottomless pit of the European Union and [European Commision chief] Jean-Claude Juncker’s wine cellar”.

The criticisms revealed growing Tory pressure for the Prime Minister to stand firm on money – even if that keeps the Brexit talks in deadlock past Christmas.

Business leaders have warned they will start to implement contingency plans to move jobs and investment out of Britain if there is no progress by the New Year.

In reply to her backbenchers, Ms May insisted there could be “no running commentary on the details of the negotiations”.

However, she also insisted she had been “very clear that the financial settlement cannot be finally settled” until the future trading arrangements with the EU are known.

Promising the Government was going through commitments “line by line”, the Prime Minister said: “We are not just going to sign up to anything, like the Labour Party.”

However, she also faced pressure from pro-EU Tories, including from former Education Secretary Nicky Morgan, who urged her to face down the no-deal Brexiteers.

“Can the Prime Minister assure us that those talks will continue and that she will not listen to those, unfortunately on these benches sometimes, who want talks to stop?” Ms Morgan asked.

Labour MP Stephen Kinnock warned of border chaos, revealing that MPs visiting Dover were told that “if you add two minutes to customs procedures, you get additional 17 miles of tailbacks”.

Meanwhile, Labour leader Jeremy Corbyn said it was like “Groundhog Day”, claiming Ms May was “too weak” to bring together “the warring factions of her own Cabinet and party”.