The Liberal Democrats are “the strongest Remain force in British politics” the party’s leader has said.
With the results for Wales and the nine regions of England declared, the Lib Dems finished in second place with 15 MEPs, up from just one at the last European Parliament election in 2014.
In a statement, Lib Dem leader Sir Vince Cable said: “Our clear, honest, unambiguous message has won us our best ever European election result, and pushed Corbyn’s Labour into third place.
“We have shown ourselves to be the strongest Remain force in British politics.
“We will always stand up for the people who have put their faith in us, taking this mandate forward to campaign harder than ever to stop Brexit.
“There is a clear lesson for Labour in tonight’s results: get off the fence. In trying to please everybody they have pleased nobody.
“With a Tory leadership contest increasing the risk of a no-deal Brexit, Britain can no longer tolerate an opposition which ducks and dives on the biggest issue of the day.
“If you want to see an outward-looking Britain, standing tall in the world with our European partners, and offering opportunity to everyone at home, there is no better moment to shape the future of our party and our politics, by joining the Liberal Democrats.”
Brexit co-ordinator for the EU Parliament Guy Verhofstadt tweeted his congratulations to the Lib Dems.
In a tweet, he said: “Amazing result for the @LibDems. Congratulations to @vincecable. I look forward to welcoming a big delegation of pro-European Lib Dem MEPs to the European Parliament. Together we will fight for a better Europe!”
The Lib Dems came first in London and second in four other English regions.
Asked if Change UK MPs should now switch sides, Lib Dem MP Jo Swinson said “anyone with liberal values is obviously welcome to join” the party.
Ms Swinson, who is expected to run for the Lib Dem leadership when Sir Vince steps down, told Sky News: “We are already working together and in Parliament, with the campaign for a people’s vote, the Liberal Democrats are working with Plaid Cymru, the Green Party, Change UK, the SNP and Labour and Conservative MPs who believe our best future is in the EU.”
She added: “These are our best ever EU election results. Uniting Alistair Campbell and Michael Heseltine in voting for the Liberal Democrats deserves commendation in itself.”