Michel Barnier has said the EU is "not in a position" to find an agreement with the UK on Brexit.
The EU's Brexit negotiator said: “To put things very frankly, though, and to try and be objective, this particular point, we are not really in a position where we are able to find an agreement.”
He added: “The thing is, though, time is pressing. We are one week away from the European Council summit.”
He said the British proposals for alternatives to the backstop have lead to “serious concerns”.
He said: “First of all, the issue of the border and checks on goods on the island of Ireland. Prime Minister Johnson has always been very clear in rejecting the backstop, which is a sort of insurance, a safety net that we had come to an agreement with with Theresa May’s government. So that is one point.”
Mr Barnier said the UK’s proposals for border checks avoiding physical infrastructure are “a system that hasn’t been properly developed, that hasn’t been tested”.
Addressing the European Parliament, Jean-Claude Juncker said Brexit was the choice of the British people, and not the choice of the European Union.
“Although we are respecting that choice. As it stands, we will remain in discussion with the United Kingdom on the terms of its departure.
“And, personally, I don’t exclude a deal. We are, Michel and myself, working on a deal.
He added: “We will see in the next coming days how things will develop.”
Mr Juncker said: “I would like to repeat to the attention of our British friends that there is not only a parliament in Westminster which has to agree, there is a parliament here.”
Earlier, Brussels had warned Boris Johnson that Britain will still be liable to pay into the EU budget until the end of next year, even if it leaves without a deal on October 31.
EU budget commissioner Gunther Oettinger said the UK had fully signed up to the budget for 2020 – its final year of contributions – regardless of whether there was an agreement.
Speaking at a news conference in Brussels, he said that, even if the UK refused to pay up immediately, officials were sure they would get the money “at a later stage”.
“In the 2020 draft budget, the UK is a full partner with all rights and obligations in terms of monies paid and monies received, and that is how we understand the law because the MFF (multi-annual financial framework) to the end of 2020 was agreed with the UK,” he said.
“If the British are not prepared to pay, we are sure we will get the money at a later stage, but not immediately.”
Mr Oettinger acknowledged that any refusal by the British to meet their obligations would cause problems for the EU, with €11bn set to “provisionally disappear” from its budget plans.
He said emergency plans to meet the shortfall had been drawn up, with half being met through budget cuts and the rest from “further revenue”.
He added however: “We are still working on the assumption that, when the UK leaves, they will do so in an orderly fashion and will meet their rights and obligations next year, their final year in the budget.”