A hard Brexit could ground UK planes for up to three weeks but would be survivable for Ryanair, the airline's CEO Michael O'Leary said ahead of a meeting of European Union leaders in Brussels. 

"We can ground airplanes for a week, two weeks, three weeks. It would be very painful," Michael O'Leary told Reuters in Berlin. "But we are a big company, we can survive." 

The Ryanair boss had warned last month that there were no assurances that an agreement would be in place enabling flights to continue after Britain exits the European Union next March. 

Michael O'Leary also said today that he did not expect Ryanair to grow in Germany next year, after closing its bases in the northern city of Bremen and at Weeze near Duesseldorf. 

"Our traffic will be flat," he said.

Mr O'Leary reiterated that he was confident that Ryanair could resolve its dispute with German unions representing pilots and cabin crew. 

He said talks were making progress and that he did not expect further labour strikes in the coming weeks.