London (Reuters): The European Union's 27 leaders will meet on April 29 to agree their negotiating lines for Brexit talks after London sends in a formal notification that it wants to leave the EU , the chairman of the summit Donald Tusk said on Tuesday.

The meeting is a necessary step before the negotiations between Britain and the 27 remaining EU states can start formally. "I will call a European Council on Saturday, the 29th of April , to adopt the guidelines for the Brexit talks," Tusk told reporters.