SIPTU says a proposal received from Aer Lingus management regarding staff tems and conditions in the event of an IAG takeover of the airline, does not go far enough.
In a statement, the union says although there's been some movement by management, overall it is too vague and conditional to form a sound basis for discussions on the issues of concern.
SIPTU members in Aer Lingus are seeking a Registered Employment Agreement or similar committment.
However, they say the management proposal doesn't go far enough and in key respects is ambiguous.
Unless there can be robust guarantees, SIPTU says the Government should not consider selling its stake in Aer Lingus.