Ryanair has reported an increase in third-quarter profits but warned of further disruption to flights as it seeks to thrash out deals with unions across Europe.

The Irish carrier, the largest operator out of Stansted Airport, posted a 12% rise in net profit to 106m euros (£93.5m) in the three months to December 31.

Revenues grew by 4% to 1.4bn euros while passenger numbers rose 6% to 30.4m during a period in which Ryanair was forced to cancel many flights after mismanaging pilots’ annual leave.

The debacle, which affected 700,000 passengers, came alongside pilot strike action and Ryanair has since pledged to increase pilot pay by 20% and beef up its cabin crews, a move that will see staff costs rise by an additional 45m euros (£39.7m) this year.

The airline also agreed to recognise the British Airline Pilots’ Association (Balpa), the trade union representing pilots.

But Ryanair warned today: “As we finalise union discussions along similar lines to that agreed in the UK, we expect some localised disruptions and adverse PR so investors should be prepared for the same.”

The group also pointed to European airline consolidation and bankruptcies, such as Monarch, Air Berlin and Alitalia, which, it said, are providing more growth opportunities in the UK, Italy and Germany in particular.

Boss Michael O’Leary said: “We are pleased to report this 12% increase in profits during a very challenging third quarter.

“Following our pilot rostering failure in September, the painful decision to ground 25 aircraft ensured that punctuality of our operations quickly returned to our normal 90% average.

“While union recognition may add some complexity to our business and may cause short-term disruptions and negative PR, it will not alter our cost leadership in European aviation, or change our plan to grow to 200 million traffic per annum by March 2024.”

The group also announced a 750m euro (£661.3m) share buyback and maintained its full-year profit guidance in the range of 1.4bn euros (£1.24bn) to 1.45bn euros (£1.28bn).