Donald Tusk has told MEPs a long extension to the Brexit process allows for “all options” to remain on the table, including the possibility of a second referendum.

In reference to claims from Brexiteers such as Jacob Rees-Mogg in recent weeks, Mr Tusk added: “I know that some have expressed fear that the UK might want to disrupt the EU‘s functioning during this time.

“But the EU did not give in to such scaremongering... in fact, since the very beginning of the Brexit process the UK has been a constructive and responsible EU member state. So we have no reason to believe that this should change.”

The European council president also warned those opposed to Brexit not to "give in to fatalism" by accepting the UK's departure from the bloc, as he said both Europe and Britain needed "dreams and dreamers".

“During the European Council one of the leaders warned us not to be dreamers and that we shouldn’t think that Brexit can be reversed,” Mr Tusk told MEPs in Strasbourg.

His remarks came as Jean-Claude Juncker, the European Commission president, said the EU had "nothing to gain" from the disruption a no-deal Brexit would bring to the UK.

He said he had adopted the "necessary contingency measures", but said only those who seek to undermine the global legal order would benefit from such an exit. "We have adopted the necessary contingency measures and we are ready for a no-deal Brexit," he told MEPs.

"But our union has nothing to gain from great disruption in the United Kingdom. The only ones who would benefit are those who resent multilateralism and seek to undermine the global legal order."

Mr Juncker made the comments as he addressed the European Parliament in Strasbourg on last week's European Council summit at which Theresa May was offered a six-month Brexit delay.

Elsewhere, it also emerged that more than 3,000 people had applied to stand as candidates for Change UK during the European Parliament elections on 23 May, as it was officially registered as a political party by the Electoral Commission.