The UK could begin the formal process of leaving the European Union early next year, European Council President Donald Tusk said.
Following the referendum result in June, no specific date has yet been given for when the government will trigger article 50 of the Lisbon Treaty to begin the withdrawal from the bloc.
But at an informal EU summit in Bratislava, Mr Tusk said Prime Minister Theresa May had told him she expects to begin the process in early 2017.
He said: “Prime Minister May was very open and honest with me.
“She declared that it's almost impossible to trigger Article 50 this year, but it's quite likely that they will be ready maybe in January, maybe in February, next year.”
He admitted Britain’s vote to leave was a “sad moment” for Europe, but said Brexit negotiations must prioritise the interests of the countries that remain members of the EU and “not the leaving country”, Sky News reported.
European Commission president Jean-Claude Juncker also set out his position on the forthcoming Brexit talks at the summit.
He said there was no possibility of the UK gaining access to the single market without accepting the free movement of people.
“There is a clear interlink as we made clear at the very beginning between the access to the internal market and the basic principles of the internal market – namely the free movement of workers and we are sticking to that position," he said.
“This is not a game between prime ministers leaving and prime ministers remaining, this is about people in Europe. So I cannot see any possibility of compromising on that very issue.
“We want to have very good, very close relation with the UK. At the same time, it is not possible for these negotiations to damage our interests.”
Speaking earlier, Mr Tusk told European leaders the UK’s referendum result was due to “failures” of British politicians.
He said national leaders had a responsibility to the EU, saying: “It also means refraining from the constant accusations aimed at the Union, which sometimes are justified, but more often than not they serve as an easy excuse for one's own failures.
“This was also one of the reasons behind the Brexit vote.”
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