The European Commission President, Jean-Claude Juncker has warned that the two-year Brexit process may take longer than expected. It comes amid ongoing disputes during negotiations which have heavily delayed trade talks.
Speaking from Luxembourg, Juckner said that the UK would also "have to pay" the divorce bill before talks can move onto trade negotiations.
A leaked document that emerged on Friday (13 October) suggested that some EU officials were prepared to start discussing trade from December but divisions between the two sides suggest that this may not be the case.
On Thursday, concluding the fifth round of talks between Britain and the EU, while both sides admitted that progress had been made, the chief EU negotiator, Michel Barnier, said that the ongoing debate over the divorce bill was "deeply disturbing."
Juncker said: "The British are discovering, as we are, day after day new problems. That's the reason why this process will take longer than initially thought.
"We cannot find for the time being a real compromise as far as the remaining financial commitments of the UK are concerned. As we are not able to do this we will not be able to say in the European Council in October that now we can move to the second phase of negotiations.
"They have to pay, they have to pay, not in an impossible way. I'm not in a revenge mood. I'm not hating the British."
Despite Britain voting to leave the EU in June 2016, little progress has been made in negotiations, with Brussels refusing to move onto trade until issues such as the Irish border, citizens' rights and the divorce settlement are finalised.
The activation of Article 50 in March this year means that there is just a year and a half left until Britain is set to leave in March 2019, a timescale that Theresa May has been adamant about sticking to.