The European Green party has urged the UK to consider rejoining the EU and draw a line under the “political and economic failure” of Brexit.

A text declaring that “the United Kingdom’s future lies in the European Union” was adopted by a large majority of European green parties at the movement’s annual leadership meeting on Friday, the day before Europe Day.

Insiders said it was the first time a European political party had officially invited the UK to rejoin the EU. “Somebody has to trigger the debate,” Vula Tsetsi, the European Green party cochair, said in an interview.

“The main discussion belongs first and foremost to the democratic debate in the United Kingdom and we don’t want to take that place, but we would like to trigger that debate as a European political family. Maybe other political families will join, but for us the moment is now.”

The intervention came after Keir Starmer’s Labour party suffered heavy losses in local elections at the expense of Nigel Farage’s Reform party gains, while the Greens appeared to be struggling to convert increased votes into seats.

The text on reversing Brexit was part of a broader declaration by European Green party leaders calling for energy independence and action to counter the far-right.

It states: “Brexit has been a political and economic failure with lasting negative consequences for people in the United Kingdom and across Europe.

“The European Green family is clear: the United Kingdom’s future lies in the European Union. We stand ready to welcome the UK back alongside other countries when it chooses this path.”

The declaration means that green parties across Europe, such as Die Grünen in Germany or Les Écologistes in France, to use their short names, should reflect this position in national debates and policy positions.

Delegates from 30 European green parties gathered in Brussels on Friday to approve the text, including those from non-EU member states. Representatives from the British green parties were not present because of the local and parliamentary elections, but were entitled to take a position on the paper remotely.

The Green party leader for England and Wales, Zach Polanski, has described Brexit as “a sledgehammer to an already weak economy” and told ITV’s Peston show that he was “firmly, very much in favour” of rejoining the EU eventually. He discussed the rejoin declaration with Tsetsi and the fellow European Greens cochair Ciarán Cuffe at a meeting in Manchester on 1 May.

A spokesperson for the Green party of England and Wales said: “Brexit has been a disaster and we have always said we should rejoin the EU when the political circumstances are right.”

The intervention could intensify the debate inside the UK about closer economic ties with the EU, amid a looming downturn caused by the US-Israeli war on Iran, Donald Trump’s criticisms of Keir Starmer, and heightened awareness of Russia as a security threat.

However, the Greens are represented in few EU governments, and no other European political parties are expected to follow suit.

The influence of green parties across Europe has diminish in recent years, highlighted by losses in the 2024 European parliament elections and their ejection from Germany’s governing coalition.

Tsetsi insisted the Greens fortunes were rising again, pointing to recent election results in Denmark, votes in the UK and mayoral contests across Europe – Greens and affiliated parties picked up mayoralties in Riga and Copenhagen in 2025. “This is a moment where Greens are picking up … and they are able to influence the political debate,” she argued.

The veteran Greek politician brushed aside suggestions that the UK had been a difficult member state, saying times had changed. “History shows that Brexit was a mistake and both sides lost a lot. And I am very confident that we will be able to learn from the mistakes and to build a stronger European Union together.”

The political situation, she stressed, had evolved since the Brexit referendum in 2016: “This is a historical moment again … Ten years after Brexit took place, Europe needs to be reinforced.”