David Davis has risked a backlash from Tory MPs after indicating Britain will not refuse new EU rules in the Brexit transition period, when the UK has no power to shape them.

He suggested the Government would rely instead on the EU taking a long time to implement new rules during the likely two-year period after 2019, in the hope that by the time any come in to force the transition will be over.

But his answer was immediately dismissed as “really rather weak” by a senior Conservative backbencher who grilled the Brexit Secretary during a committee hearing on Wednesday.

Mr Davis’s reluctance to say the UK will refuse fresh EU rules also sets him on a collision course with Foreign Secretary Boris Johnson, who has said the country must not take new regulation after 2019.

It comes just days after The Independent reported how a senior parliamentarian in Brussels said UK negotiators had already agreed in principle to a transition that will see the country continuing as a member in “all but name”.

During a hearing of the Brexit Committee, one of its members, Jacob Rees-Mogg, asked Mr Davis if the UK would accept new rules laid down by the European Commission during the transition period.

The Brexit Secretary said: “Ah now, that’s an area of some interest, because the time to take to put a rule into effect, a regulation into effect, in the EU, the average is 22 months.

Brexit: the deciders Show all 8 1 /8 Brexit: the deciders Brexit: the deciders European Union's chief Brexit negotiator, Michel Barnier Getty Brexit: the deciders French President Emmanuel Macron Getty Brexit: the deciders German Chancellor Angela Merkel Reuters Brexit: the deciders Commission President Jean-Claude Juncker EPA Brexit: the deciders The European Parliament's chief Brexit negotiator Guy Verhofstadt Getty Brexit: the deciders Britain's Prime Minister Theresa May Getty Images Brexit: the deciders Britain's Chancellor of the Exchequer, Philip Hammond PA Brexit: the deciders After the first and second appointed Brexit secretaries resigned (David Davis and Dominic Raab respectively), Stephen Barclay is currently heading up the position PA

“The proposal we have for the European Union is that we leave after 21 months – in other words, there would be nothing that we didn’t have a say in.

“Now, what happened is not right, where it doesn’t work out that way, we’ll see when we come to it.”

Mr Rees-Mogg responded: “Isn’t that a really rather weak answer – to say that the EU has been slow at implementing new laws in the past and therefore it will be slow in the future, when it has a 21-month period when it can implement new rules, possibly including a financial transaction tax, and that it may suddenly find there is an incentive to move quite quickly?”

Mr Davis said he would not go further into the matter as it may risk him skewing ongoing negotiations with the commission.

But his cabinet colleague Mr Johnson said in an interview last year that the Prime Minister said “very clearly in Florence that she envisages the transition period being run under existing arrangements” and that meant only agreeing to existing rules, rather than new ones.

Earlier in the committee session, the Brexit Secretary also confirmed that the UK would be “happy” to accept the oversight of the European Court of Justice during the likely two-year period after 2019.

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Mr Rees-Mogg asked: “If on 30 March 2019 the UK is subject to the European Court of Justice, takes new rules relating to the single market and is paying into the European budget, are we not a vassal state?”

Mr Davis denied the assertion, arguing that it was not valid because, while the UK would accept the court’s jurisdiction with “automatic effect” and without having a representative on it, it would only be for a “short period”.

Despite Ms May having indicated she wants an “implementation period” in which EU-UK trade operates on “current terms”, an agreement that maintained the broader status quo could drive a wedge through her party.

But the prospect appeared a step closer after Belgian MEP Philippe Lamberts told The Independent this week that UK negotiators are going along with proposals that mean after Brexit in March 2019, Britain will continue as a member of the EU in “all but name” until at least December 2020.