The Turnbull government's tough public service industrial policies are under renewed pressure after Labor, the Greens and independents teamed up in the Senate on Thursday to force an inquiry into the three year-pay and conditions dispute.

Tasmanian Independent Jacqui Lambie joined Labor's Doug Cameron and the Greens' Lee Rhiannon to have the government's handling of the dispute investigated by the Education and Employment References Committee, with a report due by the end of November.

The motion passed the Senate with the support of the Nick Xenophon team voting block.

Now Public Service Minister Michaelia Cash and her senior bureaucrats will face several grillings in public committee hearings over their handling of the dispute.

Speaking against the motion in the Senate on Thursday, minister assisting the Prime Minister James McGrath said public servants had been offered workplace deals that were "reasonable and responsible" and attacked the public service's main workplace union, the CPSU.

"The CPSU still refuses the government's reasonable pay offer meaning that some public servants have not had a pay rise for almost three years," Senator McGrath said.

"Unfortunately, the union remains more interested in organising and promoting industrial action than in ensuring their members receive a pay rise."

Public servants at agencies and departments employing more than 100,000 workers are still resisting, after three years, a push to impose new enterprise agreements developed under the hardline Abbott-era public sector bargaining framework.

The committee's findings or recommendations will not be binding on the government but the process will present another headache for Senator Cash in the marathon public service dispute.

The government's policy faces legal scrutiny in the Fair Work Commission after the dispute at the Immigration Department and Border Force was ordered into arbitration last week, with the commission also ordering a halt to damaging strikes at air and sea ports around Australia.

The commission has also asked another 10 departments and agencies to enter conciliation with union representatives in a bid to settle a Community and Public Sector Union legal challenge to Employment Minister Michaelia Cash's handling of the dispute.

The senator's office did not respond before deadline on Thursday

The Community and Public Sector Union was quick out of the blocks after Thursday's Senate vote, saying the committee would try to establish why the dispute was still not resolved after more than three years.

"This is an important opportunity to find out why the government has blocked progress on bargaining for so long and why the minister and the Public Service Commission have refused to find a sensible solution to a dispute which has run for over 1000 days." CPSU national secretary Nadine Flood said.

"This is the first Australian government in 30 years which has been unable to conclude public sector bargaining and that has tried to starve workers into accepting cuts to family friendly and other rights and which has refused to sit down at the table and negotiate outcomes in good faith.

r the Australian community."

The committee will look at "the failure of the government to conclude workplace bargaining across the Australian Public Service almost three years after the process began – a process that has impacted on more than 150,000 staff nationally and 115 agencies during this time ]and] the impact of the protracted dispute on service provision, particularly in regional Australia, and for vulnerable and elderly people."

The committee will also look at the impact on Australia's tourism industry from the air and seaport strikes, the hit to public service staff morale and to the working conditions and entitlements of public servants.