Ryanair has offered senior pilots who agree to work an additional 10 days a bonus of up to EUR 12,000 in a bid to avoid additional passenger disruption after it canceled more than 2,000 flights over staffing issues.

The Irish airline has been widely criticized by politicians and consumer groups since announcing on Friday plans to cancel between 40 and 50 flights per day in the weeks to Oct. 31.

Chief Executive Michael O'Leary said the cancellations were caused by a transition to a new system of allocating leave to pilots, but he denied suggestions from a pilot group that it has a deeper problem in hiring and retaining pilots.

Ryanair on Monday said it was preparing for up to EUR 20 million (US$23.9 million) in compensation claims and 5 million euros in lost fares as a result of the cancellations, although analysts estimated the total cost could be higher.

It has also brought a wave of bad publicity for an airline which has worked hard over the past few years to improve a reputation for treating passengers badly.

A letter sent to pilots on Monday, whose contents were confirmed by Ryanair on Tuesday, offered 12,000 euros gross to captains and 6,000 euros to first officers, to be paid in November 2018.

"To avoid further cancellations, we are requesting between 1 and 2 blocks of 5 days from every pilot who has already been assigned their Monday off," Chief Operations Officer Michael Hickey said in the letter.

As well as working 10 additional days, the pilots must fulfill several other conditions, including that the pilots in question fly over 800 hours in the year to Oct. 31, 2018, and have fewer than four unauthorized absences during the period.

The pilots must not have resigned before that date, the letter said.

Ryanair will also increase the payments that pilots receive when they spend a night away from their home base to 75 euros from 28 euros, the letter said.