Commonwealth bureaucrats based in northern Australia gave evidence to the the committee examining the handling of the three-year bargaining saga in Townsville on Tuesday with one Defence official saying he and his colleagues felt they were under siege from their department's senior management.

Defence public servant and former police officer Ian Reid told the hearing of the anger and disillusion felt about the stalled bargaining process by he and his co-workers at a north Queensland military installation.

Defence's 18,000 public servants are among about 97,000 who have still not signed up to deals offered under the Coalition's tough public sector bargaining framework after their previous workplace agreement expired in 2014.

Defence voted in March to reject a deal developed under the Coalition's tough public sector workplace bargaining framework. The no-vote margin was just two per cent. The department workforce voted no again in May, with an increased margin of 10 per cent.

Departmental employees were told in October that bargaining had reached an impasse and that a fresh vote would be scheduled as soon as possible.

Mr Reid said, who runs the ADF's Army cadet program out of Lavarack Barracks in Townsville, said he and his colleagues were highly critical of the approach taken by senior departmental leadership to the bargaining process.

"Our staff feel undervalued, we work really hard to provide a very professional result but we believe we're not being consulted, we believe we've been lied to," Mr Reid said.

"The attrition by siege mentality seems to be the position my superiors are coming from."

CPSU activist and Defence Department human resources officer Deb Hayman told the committee previous rounds of bargaining had been conducted with both sides working together to try to achieve a negotiated outcome that worked for all the parties.

"The current bargaining policy goes against this fundamental tenet and has destroyed the relationship between Defence and its APS employees," Ms Hayman said.

"There is a strong feeling of disrespect in the workforce and an anger that has built that I have never seen before.

"Employees do not feel valued, trust has eroded significantly and morale has continued to decline in the two-and-half years this process has been going on."

Ms Hayman said her own experience reflected the findings of official departmental surveys showing morale was low among public servants at Defence.

"With my HR hat on, I'm seeing an increase in stress-related injuries to people," she told the senators.

"They [the workers] really want to go out of their way and help the ADF, they're 100 per cent committed in that area."

Ms Hayman said she was seeing an increase in absences, a decrease in engagement and more and more Defence public servants saying they did not care.

"Which is actually quite concerning because Defence APS employees have always cared, they've always cared a lot," she said.