Tens of thousands of federal public servants are facing a cut in real wages, following the Government's below-inflation pay deal for the Defence Force.

The Defence Remuneration Tribunal yesterday approved the Government's offer of an annual 1.5 per cent pay rise for uniformed members of the Australian Defence Force (ADF) over three years.

Military personnel and their families have expressed frustration at the cut which comes shortly after the deployment of troops to the conflict against Islamic State militants in Iraq.

Prime Minister Tony Abbott said while he regretted the decision, it was appropriate in the current fiscal environment.

"There's going to have to be very tight pay restraint across the public sector, including Defence personnel," he told reporters in Sydney.

"I regret that but you can't do as much with a $40 billion deficit than you could with a $20 billion surplus and obviously until we get the budget back under control, there has got to be general pay restraint across the public sector.

"I'd be surprised if anyone in the Commonwealth public sector received more than anyone in the Defence Forces."

The deal for ADF members is just the start, with the Government negotiating new pay deals with 70 agencies, including the Department of Human Services which has been offered a pay rise of less than 1 per cent a year.

The 15,000 members of the Community and Public Sector Union (CPSU) who work in the department are now voting on whether to take industrial action over their stalled negotiations.

Alistair Waters from the CPSU said there was growing unrest among public servants about the Government's negotiating style.

"This is not just about pay, it's a smash and grab on [the Government's] part attacking worker's rights and conditions," he said.

Staff at a second agency - the Department of Veterans' Affairs - are also threatening industrial action.

The CPSU has lodged an application in the Fair Work Commission for a ballot of staff in the department to take protected action.

"This is a very serious situation and we will see that developing in future months," Mr Waters said.

"Public servants are strong and are prepared to stand up for their rights."