Theresa May was accused of "Brexit betrayal" by Ukip on Wednesday after she asked the European Union to consider a longer transition period.

EU freedom of movement and the supremacy of European judges over British courts could drag on even longer after Brexit, following the UK's request.

But Gerard Batten, a Ukip MEP and the party's interim leader, said: “This is Brexit betrayal at its contemptible worst. It’s time for May to go and for a genuine Brexiteer to step up for role of Prime Minister.

"I’ve warned that closet Remainers such as May will delay and impede Brexit in the hope of later overturning the democratic wishes of the people. This is barefaced treachery and cannot be allowed to stand," added Mr Batten.

The European Commission wants the transition period, which will prolong the status quo for about two years after the 29 March 2019 Brexit deadline, to finish at the end of 2020.

During this time Britain will be stripped of all EU voting rights while being forced to observe all existing and new European rules, reducing it – in the view of some Brexiteers – to a “vassal state”.

“The UK believes the period’s duration should be determined simply by how long it will take to prepare and implement the new processes and new systems that will underpin the future relationship,” a British government paper shared with EU-27 diplomats said today.