There are growing fears for the future of the Croke Park deal as the biggest public service unions in the country prepare to release the results of ballots by members.

Results from SIPTU, IMPACT and the INTO are due later and informed sources have indicted the SIPTU result is too close to call.

So far 8 out of 20 unions have rejected the deal which will bring about changes in work practices including longer hours and less pay.

IMPACT members are expected to endorse the deal but informed sources say the result from the country's largest Union SIPTU is too close to call.

The government has warned it will legislate for across the board pay cuts of around 7% if unions don't accept Croke Park.

Such a move is likely to provoke an angry response from the country's public servants.