German Chancellor Angela Merkel told Britain on Thursday not to have any "illusions" that it would have the same rights as an EU member after it leaves the bloc.
"A third-party state will not have the same rights or even superior rights to a member state," Merkel said ahead of a Brussels summit on Brexit on Saturday.
"This may sound self-evident, but I have to say this clearly because some in Britain seem to have illusions on this point," she told the German parliament.
"That would be a waste of time."
Merkel said that talks from the very start must include Britain's financial obligations, including after Brexit.
She also said that the conditions of Britain's EU exit must be resolved first in a "satisfactory" way before negotiations turn to its future relations with the bloc -- a sequence Merkel called "irreversible".
The leaders of the other 27 EU nations will meet on April 29 to set down the bloc's "red lines", although the talks will not begin until June.
"The negotiations will be very demanding, without doubt," said Merkel, the leader of the biggest EU economy.
The EU has toughened its strategy, making new demands over financial services, immigration and the bills Britain must settle before ending its 44-year-old membership of the bloc.
The EU's latest draft negotiating guidelines, agreed on Monday, point to months of difficult talks ahead as Brussels seeks to ensure Britain does not get a better deal outside the bloc than inside.
According to the document seen by AFP, the other EU countries will seek to hold Britain liable for the bloc's costs for at least a year after it leaves in 2019 -- longer than was previously proposed.
Earlier this week, a German senior finance official pointed to some of the "tough issues" ahead, in an interview with AFP.
"What won't work is having access to the internal market without freedom of movement" for EU citizens, said Jens Spahn, state secretary at the finance ministry in Berlin.
"Or access for UK financial institutions to the European financial market if at the same time there is rampant deregulation in London.
"You can have either one thing, or the other. These things must be clarified."
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