Theresa May could be facing “very serious opposition” from the European Union in her bid to reopen the Brexit withdrawal deal, Romania’s ambassador to the UK has said.

While Dan Mihalache said it was “hard to say” if Mrs May would be successful in her demands for this, he warned “the mood is not essentially positive amongst many European partners”.

The ambassador spoke about the prospects when he was questioned by MSPs on the Scottish Parliament’s Europe Committee.

Asked directly if the withdrawal deal could be reopened, he said: “I believe now the European Union waits your step, it is your turn. We will see .. how to express it … the ball is in your field.”

Mr Mihalache added: “It is complicated to give an opinion, to give you my opinion about this, but you never know.

“As I said before don’t think that the mood is very positive in some political circles in Brussels, for various reasons, and there could be serious opposition.”

He made clear to the MSPs that Romania regarded the UK’s decision to quit the EU as a “great loss” and also told how Brexit could be “symbolically very dangerous” for the remaining 27 states.

Romania has taken on the presidency of the EU Council – which is held on a six-month rotating basis – during “times that are very, very complicated,” Mr Mihalache said.

But he told the committee: “I can assure you from the Romanian presidency’s point of view, we will act as an honest broker and we will try to orientate the debate amongst member states to a positive approach to the relations with the United Kingdom, to get to an orderly withdrawal of the United Kingdom.

“The future of the relations is in your hands, mainly.”

Romania joined the EU at the start of 2007, with the ambassador saying: “For an older generation like mine which experienced the communist regime, belonging to the European Union is a great achievement of our political generation.”

He told how he had arrived in London the day after the 2016 European referendum, saying: “Since then I am trying to follow this debate on Brexit and I must confess … that sometimes I am very confused.

“I don’t know what the future will be, there are so many complicated questions and my feeling is now time is running very fast.

“We are in February now, theoretically there is a month to the official withdrawal and there is no solution on the table.”

Asked if a deal could be finalised before the  formal departure date on March 29, he stressed this was in the UK’s hands.

He said: “I don’t see now what the solution will be, if there will be a postponing of the withdrawal.”

The ambassador added: “We stand as the presidency for a very orderly withdrawal, I believe the no deal scenario … would be probably the worst option.

“Speaking very frankly, the mood is not essentially positive amongst many European partners, you should be very aware of this.”

He made clear: “For Romania the UK leaving the European Union is a great loss, we had excellent cooperation between the UK and Romania in many fields, we stood for the same positions in foreign policy, in security policy, in cooperation in police matters, in cooperation in information exchange.

“The UK not being at the round table of decisions in the European Union, for us we are losing an ally.

“Even though there is a very optimistic feeling in the political environment in the United Kingdom that the role should be maintained, I am more sceptical.

“You won’t be at the table any more, at the table of decisions, and you have to be aware of this.”