London (AFP) - Andy Burnham put the idea of Britain rejoining the EU on the table Wednesday, breaking a taboo for a UK prime minister and leading French President Emmanuel Macron to declare in English: “Welcome back.”

Burnham reopened the divisive Brexit debate by saying his centre-left Labour government could go “all the way” and propose membership of the bloc as one possible way to boost relationships with Europe.

Right-wing rivals immediately criticised the comments, as the UK appeared to be gearing up for a re-run of the bitter “Brexit wars” that dominated politics after the contentious 2016 vote to leave the European Union.

Burnham, premier since July after Labour MPs turfed out Keir Starmer, told his party’s annual conference in Manchester on Tuesday that Britain’s departure in 2020 had done “more harm than good”.

Brexit had triggered “a decade of low growth” and the country must “decide on a long-term relationship” with its largest trading partner, he said.

Burnham promised to set out “different options” closer to a planned summit with the 27-member bloc later this year.

Possibilities that could be looked at included joining the European single market and customs union, “or we could go all the way”, Burnham told BBC radio on Wednesday.

“We have to look at what is doable, and what would be the pros and cons of each” option, he added.

Macron, speaking in Madrid after talks with Spanish Prime Minister Pedro Sanchez, welcomed the idea.

“If the British want to come back and if the prime minister is moving in that direction, I think that is very good news both for his country and for Europeans,” Macron said.

“Come back,” he added.

Sanchez echoed Macron’s comments, saying if the UK asks to rejoin “then of course Spain would applaud it and open its arms again to a brotherly people”.

European Commission spokesman Balazs Ujvari said it was for London to chart a way forward.

“We remain open to engaging on the options it may put forward,” he said.

- Brexit polls -

Britain’s right-wing Conservative party took the country out of the EU after Britons voted to leave by 52 percent to 48 percent.

A poll by Survation in June found that 55 percent of voters would opt to rejoin if a referendum was held again.

“I think Burnham is recognising the widespread view in the country that Brexit has failed,” David Henig, an expert on UK-EU relations, told AFP.

Burnham is currently bound by Starmer’s 2024 election-winning manifesto which ruled out joining a customs union, going back into the single market or allowing the return of freedom of movement with the EU.

He suggested to broadcaster ITV that if public opinion is “pointing towards” backing re-entry into the bloc, he might commit to another referendum in Labour’s next election manifesto.

The next general election is not expected until 2029.

- ‘Divisive’ -

Sandro Gozi, a European lawmaker who chairs a parliamentary initiative on EU-UK relations, told AFP Burnham’s willingness to explore options offered a “historic opportunity” for the European Union.

But Anand Menon, director of the UK in a Changing Europe think-tank, was more cautious.

“All he seems to have said is: ‘We’ll have a conversation about it now’. There are quite a few people in his cabinet who would not want to see him spending a lot of time and effort dealing with Europe,” he told AFP.

Richard Tice, deputy leader of the anti-EU Reform UK party, said Burnham was “trying to sneak us back into Brussels via the back door”.

Public opinion appeared mixed on the streets of Manchester, during the party conference there.

Dougie Brown, a 38-year-old composer, warned: “It will be divisive again.

“I think there’s so many other things we need to be sorting out rather than fighting about whether we’re in the EU or not.”

But stall owner Sally Jones, 52, said: “I’d like us to fully rejoin. I don’t think there should be restrictions on travel for people. People coming to this country and us into Europe.”

- Reform criticism -

Burnham has previously said he hoped Britain would return to the EU within his lifetime.

But during his successful campaign to return to parliament in June and replace Starmer in Downing Street, he insisted he did not want to “rerun” the Brexit debate.

The UK-EU summit may now be held in November, but no date has been confirmed.

Negotiations are believed to have stalled over British concerns about the EU’s “Made in Europe” plans to protect certain industries.