Union members at Irish state airline Aer Lingus warned Wednesday they may take strike action after Easter if they do not reach a deal with the carrier on pensions and job security ahead of its privatization.

Ireland's biggest union said it had served notice of industrial action on Aer Lingus which would come into effect in two weeks, ruling out a strike over the busy Easter holiday period.

"The notice will therefore only come into effect after the Easter period on the expiry of two weeks' notice from today," the Services, Industrial, Professional and Technical Union (SIPTU) said in a statement.

The Irish government on Tuesday backed plans to sell a 60 percent stake in the airline and said corporate advisers were aiming for a stockmarket listing "as soon as possible".

SIPTU members at the airline supported industrial action in a vote last week.

The union said its members would take strike action if Aer Lingus was privatized without guarantees there would be no compulsory redundancies and outsourcing. It also wants an agreement on pensions and job security.

Aer Lingus said in a statement there was still work to do to deal with staff concerns but it was confident the sale would go ahead over the "coming months".