The staggering price rejoining the EU could cost British taxpayers, revealed

Its central estimate puts the figure at around £34billion, based on the European Commission’s proposed long-term budget for 2028-2034.

The analysis comes amid renewed debate over Brexit after the PM signalled that Britain should consider a much closer relationship with Brussels, including the possibility of returning to full EU membership.

Mr Burnham has argued that Brexit has “done more harm than good” and promised a “serious dialogue” and “pragmatic approach” to the UK’s long-term relationship with Europe, opening the door to options he had previously ruled out.

He said of his stance on the EU: “Our immediate priority is securing a successful outcome at the summit, and I believe we should then set up a serious dialogue about the different options for our relationship in the long term.”

He has also said the existing relationship with the EU is “not good enough”, arguing that closer cooperation could help improve economic growth and tackle immigration.

The Bow Group’s figures estimate that a gross contribution of approximately €40billion, equivalent to £34billion, would represent the UK’s share of the Commission’s proposed 2028 budget under its central scenario.

The upper estimate of €48billion, or £41billion, assumes the EU’s proposed financing rate is applied to an enlarged income base that includes the UK.

The lower estimate of €33billion, or £28billion, assumes a reduced budget ceiling and a smaller British share of the Union’s income. The report stresses that the figures are “illustrative” rather than a definitive forecast.

Mr Burnham has sought to frame the debate around the economic consequences of remaining outside the EU, rather than treating the Brexit settlement as beyond reconsideration.

In September, The Prime Minister said: “I think we have seen growth harmed by Brexit and it’s hard to see how we can get back to the higher levels of growth we once had by staying too distant from our largest market.”

During this week’s Prime Minister’s Questions, Mr Burnham was accused of “doing Russia’s dirty work” as Tory leader Kemi Badenoch demanded answers over his claim Moscow attempted to interfere in the 2016 referendum vote.

Mrs Badenoch told MPs: “This is the first time I have ever heard the head of MI5 slap down a Prime Minister for doing Russia’s dirty work for them.

“Either the Prime Minister knew what he was doing on that podcast, trying to undermine the 2016 referendum, or he opened his mouth on a matter of national security and said the first thing that came into his head.

“So does the Prime Minister agree with the director general of MI5 that talking up Russian interference was a mistake?”

Mr Burnham responded: “Well, I could ask her, Mr. Speaker whether she’s even read the Russia report yet.

“I also wonder whether she’s read the full comments from the former head of MI6.

“Because if she had, she wouldn’t have made the statements that she just made in this in this House.”

With Mr Burnham promising a longer-term discussion about Britain’s place in Europe, the cost of membership is likely to become a central issue in the debate over whether the UK should seek to reverse Brexit or pursue a less ambitious agreement with Brussels.