The European Council president Donald Tusk has written a furious public letter to a group of British Conservative MPs who've blamed the EU for reusing to guarantee the rights of UK citizens living in Europe after Brexit.
Tusk says the only way to end the uncertainty is by triggering article 50 of the Lisbon Treaty - and allowing negotiations to begin.
Our Europe correspondent Elena Casas has more from Brussels.
IN: "It's a very interesting argument…
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