Ryanair has cancelled 20 flights to and from Ireland next Friday due to the fourth day of strike action by Dublin-based pilots.

The airline said the cancellations represent 7% of the 300 Irish flights planned for the day.

It said all customers have already been notified and will be “readily re-accommodated on other flights – or refunded their fare.

Fórsa, the union representing Irish-based pilots, yesterday announced the decision to strike for a fourth day in the continuing row over seniority, base transfers and annual leave.

It said further action would follow unless the airline "changed tack" and "negotiated in good faith."

On Wednesday the airline warned that up to 300 jobs are at risk, with plans to cut the size of its Dublin fleet over the winter period.

The airline said it was reducing the number of planes based in Dublin from 30 to 24.

It issued letters of 90 days protective notice to voer 100 pilots and 200 cabin crew employees, warning that their services "may not be required" from October 28th onwards.

In a statement the union said the threat was "an attempt to put pressure on its employees."

It said it was a “provocative act, which was likely to harden pilots' resolve,” and warned it had escalated the dispute while demonstrating management's “unwillingness or inability to negotiate with unions in good faith."

Meanwhile, Ryanair cabin crew in Spain, Italy, Portugal and Belgium began their second day of strike action today.

The airline was forced to cancel up to 600 flights – affecting around 50,000 passengers.

Cabin crew staff are striking over a pay dispute with the airline.

It is the biggest strike in the airline’s history.

With reporting from Jack Quann ...