Britain "will have to pay" for leaving the EU, the president of the European Commission Jean-Claude Juncker has said.
Speaking to students at the University of Luxembourg, Mr Juncker blamed the UK for delays to the Brexit process, saying negotiations would take "longer than we initially thought".
He also said Brexit negotiations over citizens’ rights were a “nonsense”, claiming he could not understand why Britain had not guaranteed rights for European Union citizens in the UK.
Mr Juncker said the nations of Europe should be grateful for what Britain had done "during war after war", but likened the UK's failure to settle its financial obligations to the EU to someone walking out of a bar without paying, an analogy that prompted laughter from the audience.
On the question of Britain's "divorce bill" - which he previously suggested could come to around £50 billion - Mr Juncker said: "We can't find for the time being a real compromise as far as the remaining financial commitments of the UK are concerned."
Mr Juncker said the British were finding new "enormous disadvantages" to Brexit daily.
"They are discovering, as we are, day after day new problems. That is the reason why this process will take longer than initially thought," he said.
Mr Juncker was speaking after the EU's chief Brexit negotiator, Michel Barnier, said talks had reached deadlock as the UK was not prepared to indicate how much it was willing to pay in the divorce bill.
But a leaked document seen by reporters in Brussels suggested that EU leaders meeting at the European Council summit next week could authorise "internal preparatory discussions" on the shape of a future trade relationship and a transition deal, in a move which could offer Prime Minister Theresa May hope for talks by the end of the year.