Pedro Sanchez said the UK's "self-absorption" would hurt the EU and Britain alike.
Spanish Prime Minister Pedro Sanchez urged his British counterpart to call a second Brexit referendum, deploring the "great loss" the UK's divorce from the European Union would be for both parties.
"If I was Theresa May, I would call a second referendum — no doubt," Sanchez told Politico in an interview published on Sunday.
Sanchez became the most prominent EU leader to date to have urged the UK to rethink its decision to part ways with the EU with only just four months to go before it formally exits the bloc.
"It's true that we're now on the verge of signing a transition deal," he said.
"(But) I'd like to see the British government calling a second referendum. I don't mean now, but in the future, so it can come back to the EU. In another way, but back in the EU," he added
For Sanchez, Britain is a "marvellous country" which has had a "positive influence" on European politics, but the Brexit vote showed that it had strayed on a path of "self-absorption which isn't going to be good for either the UK or for Europe."
"I believe it's a great loss for both and I hope it can be reconsidered in the future," he said," he said.
EU leaders calling for second vote
Sanchez is the third, but most prominent, EU leader to have officially called for a second Brexit referendum.
Maltese Prime Minister Joseph Muscat told BBC Radio 4 in September that EU leaders almost unanimously think a second vote would be best.
"We would like the almost impossible to happen...that the UK has another referendum," Muscat said.
Talking to the same programme, Czech leader Andrej Babis said he was "very unhappy" with the UK's decision to leave.
"It will be better maybe to make (sic) another referendum and maybe the people in the meantime, they can change the view," he said.
Britons calling for second vote
In the UK, calls for a second referendum are also growing louder.
An estimated 700,000 people marched through London last month to demand a "people's vote" on the final Brexit deal in what was the UK's largest demonstration since a 2003 anti-Iraq war protest.
Taking a cue from his brother Boris, Jo Johnson exposed the rift within the ruling Conservative Party on Friday when he resigned from his role as Transport Minister in protest over the government's handling of Brexit negotiations.
But unlike his Brexiteer sibling — who quit because he thought May's Brexit proposals were too soft — Jo, a remainer, called for a vote on the final deal warning that failing to do so would be a "democratic travesty."
"My view is that this is so different from what was billed that it would be an absolute travesty if we do not go back to the people and ask them if they actually do want to exit the EU on this extraordinary hopeless basis," he told BBC on Saturday.
Referendums 'polarise societies'
In his interview with Politico, Sanchez welcomed the deal agreed between the EU and the UK to protect citizens' rights.
"I appreciate and thank very much Prime Minister May's commitment to safeguarding those rights," he said.
"We will do the same with the 300,000 Britons who're in Spain."
He also called for the approach to Brexit negotiations to be "as pragmatic as possible."
The terms of the divorce between the UK and the EU have yet to be agreed despite the deadline to do so having now been pushed back several times. Among the issues tripping up negotiators is how to avoid a hard border in Ireland as Northern Ireland is part of the UK while the Republic, in the south, is an EU member state.
"We're no closer to an agreement than three weeks ago and let's hope therefore that we can reach an agreement in December," Sanchez said.
The Spanish leader, who has to contend with secessionist calls in Catalonia, also cautioned against public votes in potential independentist regions.
"All these kind of referendums do is fragment...and polarise societies," he said.