It would leave the remaining 27 countries forced to cover the black hole in the European Union’s budget. Mr Oettinger’s stark warning that Brussels must be braced for the UK to leave without paying all of the money agreed in the “divorce settlement” raised hopes that EU leaders will agree to the concessions Mrs May needs to secure parliamentary approval for her deal. A Government source said: “As the Prime Minister has said from the outset, a good Brexit deal is in the interests of the EU as much as it is the UK, which is why we remain confident we can secure the assurances on the backstop needed to persuade MPs to back this deal, and ensure Britain leaves the EU on March 29 next year.”
EU powerhouse Germany is likely to face the heaviest burden, with a bill of hundreds of millions of euros.
Leading Brexiteers, including Jacob Rees-Mogg and ex-foreign secretary Boris Johnson, have repeatedly urged the Prime Minister not to hand over cash without future trade ties guarantees.
Mrs May made a withdrawal agreement with Brussels in November, but was forced to delay a parliamentary vote to sign it off after facing a heavy defeat.
Many Tories and the 10 DUP MPs supporting her minority government were furious about legally-binding plans for a customs arrangement that would come into force to prevent a hard Irish border if an alternative solution could not be agreed during future trade talks.
They warned that the UK could be trapped indefinitely into backstop plans.
Mrs May’s decision to delay the Brexit vote pushed her premiership to the brink before Christmas as she faced a leadership challenge, but she clung on after making a raft of promises to MPs.
She returned to Brussels and warned EU leaders it was in their interests to secure the deal, before ordering her top officials to intensify talks.
Mr Oettinger, who is responsible for the EU’s budget, told a German newspaper that the impact of a no-deal exit on the rest of the bloc would be determined by whether Britain paid all the cash agreed to cover promised budget contributions and other liabilities.
He said: “It depends on whether, following a disorderly Brexit, the British would be prepared to fulfil their rights and obligations as contributors by the end of the financial year 2019.
“If this is not the case, next year, a medium three-digit million amount will be added to Germany.”
Mrs May has told MPs the Brexit deal debate will resume after they return from the Christmas break on January 7.
The so-called meaningful vote will take place the following week.
Mr Oettinger said there is still a chance that MPs will vote to back the agreement.
And he agreed there was little widespread support for a second referendum, despite the clamour by Remainers.
He said: “It is not entirely unlikely that the British Parliament will vote for the divorce treaty in January.
“For a disorderly Brexit or for a new referendum, there is certainly no majority.”
Writing exclusively for the Daily Express before Christmas, Mrs May talked of her confidence that Brexit will be delivered on schedule next year, saying: “I know that when the British people come together, there is no limit to what we can achieve.”
Talks on future trade deals are expected to begin when Britain leaves the EU.
But echoing MPs’ demands for a “meaningful vote”, the Commons’ International Trade Select Committee called for Parliament to have a “meaningful role” throughout.
It said the Government should operate from a “presumption of transparency rather than secrecy” in negotiating post- Brexit UK trade policy.