The European Union's chief Brexit negotiator, Michel Barnier, has urged British political leaders to break the deadlock over the country’s departure from the bloc and said the week ahead would be “very important” in deciding the outcome.

He said the British government and opposition Labour Party are expected to present the results of talks on a compromise agreement in the coming days.

But he was adamant that the extended October 31 deadline can't be amended.

"This delay must not be wasted by the British. They have to make use of it to find an agreement," he told French broadcaster LCI on Sunday.

He also once again expressed frustration at the length of time taken to reach a Brexit deal.

"I observe that nothing has been done to build a positive majority on this treaty over the past year and a half,” he said. “We have just seen negative majorities and we cannot create the conditions of Britain's orderly exit with negative majorities. That is where we are now. "

He added: “This week will be very important. We will have the results of negotiations between the Labour Party and the Theresa May's government. Are these talks going to yield something?”

Asked if voters in Britain will take part in the upcoming EU-wide parliamentary elections at the end of May, Barnier said yes, if no agreement is reached before the elections.

Labour’s business spokeswoman Rebecca Long-Bailey said the government was still refusing to move on "any of their red lines" in cross-party talks.

"Honestly I think the discussions so far have been productive, they've gone into a lot of detail, there seems to be a willingness on both sides to move towards some form of consensus,” she told Sky News.

"But as yet we haven't seen the government move on any of their red lines, we're having further discussions this week and hopefully we'll see some movement."

Separately, a poll found that a majority of Scots would vote for independence from the UK if there was a no-deal Brexit.

The Panelbase survey for The Sunday Times Scotland found that Scots are 53% to 47% in favour of staying in the UK, but that reverses to 52% in favour and 48% against in the event of the UK leaving the EU without a deal.