Bus Eireann workers are expected to be updated today on cost saving plans at the company.
Reports claim the proposals, aiming to save up to €8m, will include a ban on staff overtime and an end to the practice of carrying over annual leave.
It emerged last week that a consultant's report had warned shutting down the Expressway service could be the only way to secure Bus Eireann's financial future.
Unite Regional Officer Willie Quigley says staff have been subjected to a barrage of leaks in the media.
He said: "A week has gone by and the trade unions, as I understand it, have not been offered a copy of the report.
"We also hear on the grapevine that the company is planning to call in the unions, but in the meantime these things are leaking out, and it seems to me they are being leaked out with some intent for the unions' ears in preparation for what might lay ahead when we are called in by the company."