Andy Burnham has faced accusations of “unpicking” the original Brexit agreement following his announcement that a crucial UK-EU summit next month will be utilised to pursue fresh trade arrangements with the bloc.

The summit is scheduled for Brussels on November 20, where both parties aim to finalise a new food and drink accord, a youth mobility programme and an emissions trading agreement.

On Monday, Conservative Party leader Kemi Badenoch accused the Prime Minister of exposing his strategy ahead of negotiations. She told the Commons: “What has the Prime Minister chosen to focus on today? Brexit. Here he is unpicking the deal this country signed with the EU a decade after the referendum.

“He is not going to get a better deal. The EU are tough negotiators, and it’s not just that the EU are tough negotiators, he has already revealed his entire negotiating hand. He has just blurted out everything he wants in this statement and I will tell him now, as a former trade secretary, this is not how you conduct negotiations.”

Mr Burnham’s drive for strengthened relations has received backing from figures including Mayor of London Sir Sadiq Khan. He regards Brexit as “the biggest act of economic self-harm in the history of our country”, according to a spokesperson.

“That is why he wholeheartedly supports the Prime Minister’s ambition to seek a closer relationship with the EU to put our capital, country and continent on course for a more secure and prosperous future,” the spokesperson added. “The case for rejoining the EU has never been stronger โ€“ and Sadiq is clear that immediate steps should be taken to deepen integration with our European neighbours in order to boost our economy and drive up living standards.”

Naomi Smith, chief executive of Best for Britain, which campaigns for the UK to rejoin the EU, said: “Burnham’s approach to the damage Brexit has done to Britain is a breath of fresh air for our politics, but lasting relief requires lasting change, which will only hold if politicians recognise the broad consensus of belief across the country about the future of our relationship with Europe, free from foreign interference and influence.

“It’s clear that the facts have changed and with them voters’ minds have too, but they’re not won over by halfway house measures and there’s now a clear majority in favour of EU membership โ€“ and the ยฃ92bn economic transformation it can deliver to our communities.”

Mr Burnham also took the opportunity during his Commons appearance to soften his earlier remarks suggesting Russia attempted to influence the Brexit referendum.

The Prime Minister rejected any implication that he had questioned the legitimacy of the 2016 vote, following his statement on The Rest Is Politics podcast that upon entering No 10 he was informed it was “clear” Moscow had engaged in state-sponsored interference.

“It is a matter of record that Russian actors sought to interfere in the 2019 general election and we think it is inconceivable that this was the first time,” he told MPs.