Ryanair has launched legal proceedings against its outgoing Chief Operations Officer (COO) Peter Bellew, whom low cost rival easyJet announced last month it had poached, Irish court filings showed.

Ryanair boss Michael O'Leary told staff on July 11 that Bellew would step down at the end of the year. easyJet announced his arrival as its new COO at an unspecified date a week later.

The legal proceedings were lodged in the Irish High Court on Aug. 6. No further details of the case were made available.

Asked about Bellew's departure on an analyst call last week, O'Leary said he could not comment on it for legal reasons but said all senior management at the Irish airline had pretty extensive non-compete agreements in their contracts.

"I would not expect any senior manager in Ryanair to be moving to a competitive airline for a reasonably long period of time," he said, adding the airline was in dialogue with Bellew regarding his six-month termination period.

Ryanair and easyJet said they would not comment on the matter. Bellew, who rejoined Ryanair in December 2017 after a stint as chief executive at Malaysia Airlines, could not immediately be reached for comment.