Theresa May is facing a fierce backlash across the Tory party against the idea of extending the UK’s Brexit transition period.
Former party leader Iain Duncan Smith said such a move would see the UK paying “tens of billions of pounds” extra to the EU.
The firestorm came after Mrs May signalled she is ready to delay the UK’s final departure from the EU’s hold until 2021 in a last ditch bid to end the deadlock over the Irish border issue.
Mr Duncan Smith told BBC2’s Newsnight: “I couldn’t understand why we would offer to extend the transition period when we still haven’t got anything back in return.
“By extending the backstop we are likely to fall straight into the next budget of the EU which will mean tens of billions of pounds extra to be paid across to the EU.
“It would be very hard to tell the British people that we are extending another year or more into the implementation phase, and we’re then going to pay tens of billions of pounds over when we actually say we need it for other domestic programmes.
“We are in a negotiation but at the moment it begins to look more like a capitulation than a negotiation.
“We have got to get some steel in our backbone and do something about actually negotiating, rather than saying ‘what would you like?’”
He said: “I think that so many of the things that she has told us about what she was proposing have turned out either not to be true, or she hasn’t stuck to them, so when the Prime Minister first suggested this transition, and remember what this transition is, we stay in the EU in effect, bound by all of its rules, in all of its institutions, paying our normal contribution for two years.
“We have no vote. It’s actually worse than being a member of the EU.
“She said, we are going to be in there until December 2020, not to negotiate a deal, to implement a free trade deal that would already have been negotiated.
“Now, what we hear, is that, actually, no, that’s not enough time, and, no, we are not going to be implementing.
“We are going to be negotiating that long term relationship, and now we might need a third year.
“That third year would not cost an additional ten billion euros, it might cost 18 billion euros because we’d be in the new budget cycle of the EU where all of the contributions go up.
“That is just an absolute mile from what we were originally told was necessary.”
In response, Mr Duncan Smith said: “It’s not the language I would use – but I can understand his frustration.
“I think what we’ve seen over the last 24 hours has really made people quite concerned – not only in the party, but in the country.”
Britain had originally sought a transition period ending in December 2020 after it formally exited the EU in March 2019, but EU chiefs have indicated this could be extended.
