Sir Vince Cable has claimed the support of almost one-third of EU leaders for the Liberal Democrats’ call for a referendum on the final Brexit deal.

The Lib Dem leader said that eight prime ministers – from the Netherlands, Belgium, Denmark, Finland, Luxembourg, Slovenia, Estonia and the Czech Republic – had agreed a joint statement saying that British voters should have the “final say” on any withdrawal deal.

But his claim was thrown into doubt after the ALDE grouping, which brings together liberal parties including the Lib Dems in the European Parliament, denied that any such statement had been released.

The ALDE, which organised a lunch attended by Sir Vince and his EU counterparts in Brussels, issued a tweet: “Pertaining to the Lib Dem press release issued today on Brexit: at the ALDE leaders meeting of 22 March no statement has been agreed upon or released.”

But sources close to Sir Vince insisted that the statement was verbally agreed by the leaders at the lunch, though it had not been formally signed.

The party said it was not aware of any of the eight PMs raising concerns about Sir Vince’s announcement.

And Dutch PM Mark Rutte appeared alongside the Lib Dem leader after the lunch to say: “If some way or another, the UK would decide to change its position, it would be highly welcomed by every liberal leader and, my impression is, almost everybody in the EU.

“Whether that happens will be up to the UK itself and UK politicians.”

ALDE later put out a further statement: “As a matter of fact: Vince Cable did attend the liberal leaders’ meeting and they showed support for the Lib Dems but no statement has been issued or agreed.”

The Lib Dems said that the eight leaders had backed a proposition put forward by former Belgian PM Guy Verhofstadt at the lunch, which stated: “We regret Brexit, but acknowledge the choice made by British voters for the UK Government to negotiate withdrawal.

“We further acknowledge and support the Liberal Democrats’ call for the British people to have the final say on the Brexit deal.

“All parties need to seek a broad deal accommodating both the position of the UK Government and the principles on which the European Union is built.”

Along with Mr Rutte, the Lib Dems said that the statement was backed by Belgium’s Charles Michel, Lars Lokke Rasmussen of Denmark, Andrej Babis of the Czech Republic, Xavier Bettel of Luxembourg, Miro Cerar of Slovenia, Juri Ratas from Estonia and Finland’s Juha Sipila.

Sir Vince said: “This is a clear signal from our European friends that they want us to remain in the European Union and would welcome an exit from Brexit with open arms.

“Polls show that there is a growing desire among the British public for a vote on the terms of the deal. People can now be reassured that there is no desire among EU leaders to punish us if we decided to remain in the bloc.

“The message is clear: Brexit is not inevitable.”

A spokesman for Prime Minister Theresa May responded: “We have always said that we understand that there are many countries in the EU that are disappointed by the UK’s decision to leave and we understand that.

“But we won’t be having a second referendum. We will be delivering on the will of the British people.”