Damage to Ryanair ground handling equipment at Dublin Airport is being investigated by gardai, it has been confirmed.
Ryanair's director of ground operations, Mr Conor McCarthy, claimed the incident was part of a campaign of intimidation being waged against baggage-handlers who are working normally during the dispute with SIPTU.
SIPTU last night demanded an apology from Ryanair and its public relations company for attempting to "smear the good name" of the 39 workers involved in the dispute.
In a letter to Mr Paul O'Sullivan, secretary of SIPTU's civil aviation branch, Mr McCarthy said the bulk of the airline's ground handling equipment was sabotaged between 7.30 p.m. and 8.30 p.m. on Thursday.
The Garda and Aer Rianta confirmed that the incident was under investigation.
Mr McCarthy said in his letter: "It is clear that this damage could only have been inflicted by individuals with airside security access, and such interference with the ground handling equipment of any airline is unpardonable."
The previous day Mr McCarthy had written to Mr O'Sullivan complaining that telephone threats had been received by family members of baggage staff who were working through the dispute.
Mr O'Sullivan said he was confident that union members had not been involved in any of the alleged incidents.
"SIPTU does not, nor would it ever, condone such behaviour and anybody found guilty of such wrongdoing would be disciplined under the union rules," he said.
"Regarding today's accusations, let me make it clear that following their visit to the Dail yesterday none of our members were at work last night when these incidents allegedly happened."
The Fine Gael TD, Mr Austin Deasy, has called on the public to support Ryanair rather than boycott it and condemned the reported acts of intimidation against family members of Ryanair staff.