SIPTU has confirmed that Ryanair has served papers on the union seeking an injunction preventing strike action taking place at Dublin, Shannon and Cork airports on Thursday next.
Ryanair claims the move will disrupt tens of thousands of passengers.
This evening the union said it would respond to the action in the High Court next Tuesday.
The union has also confirmed that former president of the Irish Congress of Trade Unions, Phil Flynn, is to intervene in the dispute.
SIPTU said it is willing to consider any proposal to help resolve it.
