Widespread strikes over pay and conditions a year ago forced Ryanair to cancel hundreds of flights, hitting its profits in the busy summer months. But a series of strikes in Britain, Spain and Portugal in recent weeks has caused minimal disruption.

The Irish budget airline, Europe's largest, said its first flights to and from UK airports operated with 95% punctuality, blaming air traffic control delays for the slight slippage.

Ryanair has said only around half of the pilots operating from UK airports are members of the British Airline Pilots' Association (BALPA).

BALPA, whose action on Aug 22 and 23 also caused minimal disruption, said the airline was using contractors, who are not entitled to join unions, and crews from other jurisdictions to ensure flights operated.

"The union is pleased this action has disrupted Ryanair while having minimal impact on the public," BALPA said in a statement. "We hope this second round of walk-outs will signal the resolve of our members."

BALPA said its members were seeking a pay increase and improved conditions, including a consistent and transparent pay structure, adequate pension provision, loss of licence insurance and more appropriate maternity benefits.

"So far Ryanair has made no offer," BALPA General Secretary Brian Strutton said.

(Reporting by Padraic Halpin and Conor Humphries; editing by Jason Neely and Jane Merriman)