* CEO O'Leary says no threats of industrial action from pilots
* Says does short of spare pilots in coming months

Ryanair is offering pay rises to pilots but may force some to change their holiday plans in an effort to avoid adding to 2,000 flight cancellations, though CEO Michael O'Leary denied that pilots had threatened industrial action.

The Irish airline, Europe's largest by passenger numbers, faced a wave of anger from customers after its sudden announcement last week of plans to cancel between 40 and 50 flights a day in the weeks to Oct. 31.

It said the cancelations were because of a change in the way pilot's annual leave is calculated. There are sufficient pilots to staff flights but not enough to go on standby to deal with unforseen issues and avoid flight delays, O'Leary said.

Pilots were this week offered a bonus of up to 12,000 euros ($14,290) to work 10 additional days to alleviate the shortage and O'Leary said on Thursday that pilots had collectively offered to work an extra 2,500 days since the crisis broke.

However, O'Leary denied that a large number of pilots had rejected the offer and demanded new contracts. He also denied media reports that some pilots had threatened industrial action and appeared to shrug off suggestions that employee relations could become strained.

‘Will there be squabbles with pilots? There may be. They have been happening for about 30 years,’ he said.

The pilots' letter, a copy of which was seen by Reuters, made a series of demands including the implementation of permanent local contracts under local employment law.

A source told Reuters that the letter had been approved by pilots at 17 of 85 Ryanair bases, though this could not be independently verified by Reuters.

O'Leary told shareholderings that the airline does not have sufficient spare pilots for September, October and November to ensure smooth operations and was considering forcing some pilots to change their annual leave plans.

About 500 of Ryanair's 4,200 pilots are due to take four weeks of leave in a single block in October, he said, so may be asked to defer one week of that leave until after Jan. 1.

‘There won't be more cancellations because of the rostering issues,’ O'Leary told the meeting.

He said he took personal responsibility for the operational mistakes that led to the cancellations and for the poor communication of the disruption.

Shares in Ryanair were down 0.5 percent at 16.43 euros at 1041 GMT.

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