German Chancellor Angela Merkel says some British people have "illusions" about discussing the UK's future ties with the EU at the same time as nailing down the UK's Brexit terms.
The future relationship can only be discussed once the exit issues - such as UK payments to the EU budget - are resolved, she told German MPs.
On the sequence of the Brexit talks, she said "some people in the UK still have some illusions on that score".
"That would be just a waste of time."
EU leaders are to meet on Saturday to adopt their joint negotiating position on Brexit.
The EU will "for sure" reach a free trade deal with the UK after Brexit, EU Trade Commissioner Cecilia Malmstrom said, shortly after Mrs Merkel spoke.
But the German chancellor insisted that "a third country - which is what the UK will be - cannot and will not have the same rights as an EU member state.
"All 27
EU countries and the EU institutions agree about that," she told the Bundestag, Germany's lower house of parliament.
Mrs Merkel said the immediate Brexit priorities to decide on were the rights of EU citizens in the UK and Britons in continental Europe and Britain's ongoing financial obligations.
"We can only do an agreement on the future relationship with Britain when all questions about its exit have been cleared up satisfactorily," she said.
"The sooner the UK government is ready for constructive solutions, the sooner we can meet its wish to talk about the future relationship. But first we need to know how the UK government envisages that relationship. It can only be done in that sequence."
EU officials estimate that the UK faces a bill of €60bn (£51bn; $65bn) because of EU budget rules. UK politicians have said the government will not pay a sum of that size.