Andy Burnham has committed himself to honouring Sir Keir Starmer’s Brexit red lines in a major blow to hopes that he would find a route for Britain back into the bloc.

In an interview last year when he was still mayor of Greater Manchester, Mr Burnham said he wanted the UK to rejoin the EU and there were serious hopes he would tear up Labour’s manifesto commitments not to rejoin the EU, the single market or customs union when he took over as prime minister in July.

This was further fuelled when his new minister for Brexit, Hamish Falconer, refused to rule out rejoining in the future.

Economic problems caused by Brexit were recently highlighted by former prime minister Sir John Major in an interview with The Independent, where he warned Brexit is costing the UK £100bn in trade a year and £40bn in tax revenues. Sir John said rejoining the single market should be a priority.

But a Downing Street spokesperson insisted on Monday that the red lines are still in place despite Mr Burnham making it clear that he wants to be “bolder” than his predecessor in taking the UK back to the heart of Europe.

The spokesperson said: “We remain committed to the red lines set out in the manifesto. We’re not rejoining the European Union, and there will be no return to the customs union, the single market, or freedom of movement.”

On suggestions there could be a climbdown on European students, the spokesperson said: “I won't comment on ongoing negotiations. The government is continuing to take stock of our position, and there will be a summit later in the year where progress will be set out.”

European Movement UK raised hopes there could still be a change of policy for the manifesto in the next election.

Mike Galsworthy, chair of the organisation, said: “Interestingly, the biggest opportunity for Andy Burnham lies less in how he handles Starmer's restrictions from the last Labour manifesto and much more in the bigger move he can make with the next manifesto. A promise in the next manifesto to open accession talks for full EU membership is the prize here.

“However, that doesn’t mean that the government should take its foot off the pedal at this stage. There are many real-world impactful wins to be had in breaking down as many barriers as possible during this parliament and building deep trust and relationships with the European team.

“But ultimately, Burnham needs to be thinking about what he should be shaping up to offer in any parliament beyond this one – and there is one very obvious answer to be seized.”

While on a trip to Ukraine – his first foreign visit since becoming PM – Mr Burnham signalled he intends to go further than Sir Keir on Europe.

He suggested Britain plans to take a “bolder” approach towards forging closer relations with the EU. But later, Downing Street declined to expand on what being “bolder” would mean.

It comes ahead of a UK-EU summit where issues such as youth mobility, defence, energy sharing and other deals will be up for grabs. Initially scheduled for July, the meeting has been postponed to a yet-to-be-confirmed date later this year.

Al Pinkerton, Liberal Democrat spokesperson on Europe, said: “Andy Burnham promised boldness, but instead he’s caved at the first hurdle.

"Sticking to Starmer's failed Brexit red lines is being loyal to a failed project - it will only drag down our economy even more, hit taxpayers, and hurt British businesses.

"If the prime minister is serious about building closer relations with Europe, he needs to tear up these self-imposed barriers. We need a bold new deal that will make Britain much stronger, including a Customs Union, but also most crucially taking Britain back into the Single Market."

During his overnight train journey to Kyiv, Mr Burnham also spoke to the prime minister of Luxembourg, Luc Frieden.

A Downing Street spokesperson said: “The prime minister set out his ambitions for the UK to get closer to the European Union, and both agreed on the important cultural and educational ties between the UK and Europe to deliver opportunity for the next generation of Brits and Europeans.”

Mr Burnham looks set to continue a policy started off by his predecessor Sir Keir of closer relations with the EU.

It echoes comments he wrote in the newspaper before he became Prime Minister, where he said: “I want to consolidate the progress made on the existing UK-EU negotiations and make further progress quickly, including by strengthening our co-operation on illegal migration, economic security and the broader resilience of our societies to external threats – from terrorism to AI-driven disinformation.”

During his campaign to win the heavily-Brexit voting Makerfield constituency in the by-election, Mr Burnham had said he was not in favour of the UK rejoining the EU, warning it could be a “permanent rut” of Brexit arguments.

He had previously said he wanted to see the UK back in the EU within his lifetime.

However, during the contest, he said: “My view is that Brexit has been damaging, but I also believe the last thing we should do right now is re-run those arguments. Britain will be stuck in a permanent rut if we’re just constantly arguing and people are pulling away from each other.

“It is time, surely, isn’t it, to bring people back together, to focus on what we’ve got in common, to get the growth coming to all places, so it’s felt there.

“That is what we need in this moment, and it’s really important that whatever comes out of this by-election there is a more unifying feeling about the change that we need to work towards.”

Economically, forging closer ties with Europe could provide a £92bn GDP boost to the UK, according to new economic research.

Commissioned by Best for Britain, which campaigns for full UK-EU reintegration, the research undertaken by Frontier Economics suggests at least 90 per cent of Brexit's economic hit could be recouped by the UK rejoining the EU.

Last week, a former Tory minister-turned Labour adviser claimed taking Britain back into the EU single market would win Burnham the next general election.

Nick Boles, who served as a minister in David Cameron’s government before quitting the Conservatives in 2019 over the party’s Brexit stance, added that it would help Burnham achieve a legacy to rival Tony Blair’s.

Mr Boles has urged the new prime minister to seize the opportunity created by “pretty scary” world events since 2016 to strike a deal with European Union leaders that would protect the continent and offer the UK a much-needed economic boost.