Theresa May’s plan for a two-year Brexit transition period under the same terms as EU membership could face difficulty getting through the European Parliament, it has emerged.

Manfred Weber, the leader of the Parliament’s largest political group, has said his party would oppose any plan that gave Britain the same benefits outside the EU as it had inside.

Though Mr Weber said he was broadly in favour of a transition period in principle, the leader of the European People's Party suggested such an arrangement could not be identical to EU membership.

The statement puts the German politician on a collision course with Ms May, who has said she wants a two-year period under which the UK effectively maintains its current relationship with the EU after it leaves the bloc in 2019.

But Mr Weber told the European Parliament in Strasbourg on Tuesday: “One thing is clear for us in the EPP: If we are discussing the treaty which will be asked for the contents in this House, then we will be ready for a kind of transitional period.

“But I have already got to clarify that we cannot accept that a country outside the EU will have the same conditions and the same status as inside the European Union, so there must be a difference.”

Mr Weber is one of the first senior European politicians to openly discuss what a transition period would look like. The European Commission has refused to debate the issue until sufficient progress has been made on separation issues like the divorce bill, Northern Ireland border, and the rights of EU citizens.

Manfred Weber, leader of the EPP (European Parliament)

The European People’s Party is the biggest group in the European Parliament and it would be unusual for a proposal to pass the parliament without its support. The European Parliament has a veto on the final Brexit deal and must agree any proposal before it is implemented.

The EPP is also the party that put forward Jean-Claude Juncker as its lead candidate to be European Commission president.

Brexit: the deciders Show all 8 1 /8 Brexit: the deciders Brexit: the deciders European Union's chief Brexit negotiator, Michel Barnier Getty Brexit: the deciders French President Emmanuel Macron Getty Brexit: the deciders German Chancellor Angela Merkel Reuters Brexit: the deciders Commission President Jean-Claude Juncker EPA Brexit: the deciders The European Parliament's chief Brexit negotiator Guy Verhofstadt Getty Brexit: the deciders Britain's Prime Minister Theresa May Getty Images Brexit: the deciders Britain's Chancellor of the Exchequer, Philip Hammond PA Brexit: the deciders After the first and second appointed Brexit secretaries resigned (David Davis and Dominic Raab respectively), Stephen Barclay is currently heading up the position PA

Ms May had said in Florence that the “implementation period” for Brexit would take “around two years” and that “during the implementation period access to one another’s markets should continue on current terms and Britain also should continue to take part in existing security measures”.