Angela Merkel has claimed the UK has "illusions" about the realities of Brexit and insisted talks on the UK's divorce bill from the European Union must be dealt with before negotiations on any trade deal can begin.

The German chancellor's stance puts her on a collision course with the UK, as Foreign Secretary Boris Johnson insisted Britain will not pay a Brexit divorce bill before "substantive" negotiations with the EU start.

Mrs Merkel's insistence that the terms of exit - including the issue of the bill which could run to £50 billion - are dealt with first comes ahead of a crunch meeting of EU leaders on Saturday to discuss their approach to the Brexit negotiations.

Speaking in the Bundestag, Mrs Merkel was cheered as she struck a firm tone about Germany's approach.

Mrs Merkel stressed that a "third country" - as the UK would be after Brexit - could not enjoy the same rights as a member of the EU.

She said she had the "feeling that some in Great Britain still have illusions" about Brexit and "that is a waste of time".

Highlighting the importance of settling the Brexit bill first, she said: "Without progress on the many open questions of the exit, including the financial questions, it makes no sense to have parallel negotiations over the future relationship."

Prime Minister Theresa May wants the talks to take place at the same time in an effort to get the best possible deal on trade.

Mr Johnson was not clear whether he opposed agreeing a divorce settlement or paying it before trade negotiations, but struck a defiant tone, telling BBC Radio 4's Today programme: "If you're saying that they want the money before they get any substantive talks then that is obviously not going to happen."

The Herald:

In a series of breakfast broadcast interviews, the leading Leave campaigner also defended his claim that Britain sends £350 million a week to Brussels that could otherwise be spent on the NHS, and claimed Germany blocked a UK Government request to reach an early agreement on the rights of EU nationals in the UK and British expats in Europe.

Mrs Merkel said: "We will of course do everything to minimise possible negative effects of Brexit for our citizens. In return we are of course prepared to make British citizens in Germany and other EU states a fair offer.

"They certainly are and should remain an important part of our society."

But Mr Johnson told BBC Radio 4's Today: "We made an offer by the way before Christmas that we would do a deal in advance of the negotiations, that was turned down you may recall by Germany, we're left in a position where we have to do a reciprocal deal, and we're fine with that.

"What we want to see is the rights on both sides protected."

The Foreign Secretary also defended the widely disputed slogan - emblazoned on the side of his battlebus during last year's EU referendum campaign - that "we send the EU £350 million a week, let's spend it on our NHS instead".

The claim was denounced by the official statistician as "misleading" and has since been disowned by senior members of the Brexit campaign.

But challenged over whether he stood by it, Mr Johnson told ITV1's Good Morning Britain "of course I do," and insisted the figure was "not disputed".

He described the sum as "£350 million a week which we do not currently control which could be spent on our priorities, including the NHS".

During the referendum campaign, the chairman of the UK Statistics Authority, Sir Andrew Dilnot, took the unusual step of saying he was "disappointed" that the Leave campaign persisted with the £350 million figure after being warned it was "misleading".

The figure does not take account of the UK's rebate, secured by Margaret Thatcher, or the cash returned to Britain by the EU.

Mr Johnson's comments came as a poll suggested that, for the first time since the June 23 referendum, a majority of voters think the decision to leave the EU was wrong.

Some 45% of those questioned by YouGov for The Times said that in hindsight they believed Britain was wrong to vote for withdrawal - up two points on a month ago - compared with 43% who thought the decision was right - down three points.

:: YouGov questioned 1,590 adults on April 25 and 26.

It is "not realistic" to think an agreement can be concluded within the tight Brexit timetable, according to Brussels' chief official Jean-Claude Juncker.

Mrs May hosted European Commission president Mr Juncker and Brussels' chief Brexit negotiator Michel Barnier for talks at Number 10 on Wednesday night.

European Commission spokesman Margaritis Schinas said they discussed the need for a "swift" resolution to the terms of the divorce agreement before talks can begin on the future.

He told reporters in Brussels: "President Juncker had a constructive meeting with Prime Minister May. He explained it is essential to come to a swift agreement on the orderly withdrawal of the UK from the EU.

"Preparatory work is progressing in a satisfactory manner and once agreement is reached on the terms of the withdrawal we can start debating the future relationship between the EU and the UK.

"The president thinks that it is not realistic at this stage that an agreement on the future relationship can be concluded before September/October 2018."

Although Brexit will not be final until March 2019, the process of ratifying any deal means it needs to have been concluded by autumn 2018.

Responding to Mrs Merkel's comments, the Prime Minister's official spokesman said: "We are approaching this in a constructive spirit and with enormous goodwill."

Asked whether Mrs May agreed with Mr Johnson that the UK should not pay any divorce bill until trade talks are under way, the PM's spokesman said: "The Prime Minister set out the Government's position in the Article 50 letter. The Article 50 letter was clear on that."

In her letter to European Council president Donald Tusk declaring Britain's intention to withdraw from the EU under Article 50 procedures, Mrs May said she was ready to "discuss how we determine a fair settlement of the UK's rights and obligations as a departing member state".

On the issue of timing, she said: "We believe it is necessary to agree the terms of our future partnership alongside those of our withdrawal from the EU."

Responding to Mr Johnson's defence of the £350 million figure, Labour MP Chuka Umunna, the chairman of Vote Leave Watch, said: "Boris Johnson is taking the public for fools. Nearly a year after the referendum, we have not seen a penny of the £350 million a week he and his Vote Leave allies promised.

"Indeed, the Prime Minister has refused to commit to the pledge, while Boris and the rest of the Tories voted against my amendment to the Article 50 Bill which would have delivered the £350 million more per week.

"The figure was dismissed by experts during the campaign, and it is even less credible now, as the Government acknowledges that we will make some continuing payments to the EU after Brexit.

"Boris needs to apologise to the millions of people he and his campaign misled with their dodgy figures."

Former EU trade commissioner Lord Mandelson said voters should not give Mrs May "a blank cheque for hard Brexit on June 8".

Writing in the Evening Standard, the Labour peer acknowledged that many voters who oppose Mrs May's approach to Brexit "do not see an alternative in Jeremy Corbyn".

But he said: "If there is not a positive to vote for, there is always a negative - and in this case it is to stop the Tories grabbing a runaway victory that will give them a blank cheque to do what they want.

"The most important reason to slow them down is where they are heading on Brexit. They are not yet taking the entire British economy over a cliff but unless they are checked that is a very real possibility."

Lord Mandelson said that shadow Brexit secretary Sir Keir Starmer had given Labour "wriggle room" to seek the "best economic settlement" for the UK outside the EU, which would involve remaining in the single market. If this route was taken, it is possible that Britain's desire to reform immigration rules would be "accommodated" by remaining member states, he said.

"It is clear...that Mrs May and the Tories are the favourites on June 8," Lord Mandelson said.

"This election may not result in a change of government but that does not mean there is not a real choice to be made. A strong parliamentary opposition to the Tories will stop the Prime Minister being given a blank cheque for hard Brexit."