UPDATE 2-Summer ticket fares will rise less than expected, Ryanair CEO says

(Updates with share price moves in paragraph 3)

By Julia Payne

BRUSSELS, May 7 (Reuters) - Ticket fare prices this summer are likely going to be lower than previously expected, Ryanair Chief Executive Michael O'Leary said on Tuesday, despite previous warnings that rising costs would get passed on to airline customers.

Aviation executives and analysts have said ticket prices were set to go up even more this year as capacity constraints and slower aircraft deliveries limit the amount of planes in the sky despite robust travel demand.

However, O'Leary said that prices were not rising as fast as previously assumed. Ryanair shares were down 6.4% at 1354 GMT, with easyJet and Lufthansa shares also down after O'Leary's comments.

"Looking at summer ... We thought pricing would be up 5-10%. We're heading to flat (pricing year-on-year) to 5% up, which is surprising with a lot of the Airbus fleet grounded for maintenance," he told Reporters in Brussels.

In February, O'Leary said average fares could increase by 10-15 euros in the next five years. (Reporting by Julia Payne, Writing by Joanna Plucinska Editing by Tomasz Janowski)