Senator Eric Abetz.

Public Service Minister Senator Eric Abetz. Photo: Alex Ellinghausen

The main public service union will use Fair Work laws to force the Abbott government into talks on wages and conditions for the 160,000 Commonwealth workers.

The CPSU says it has lost patience with the delays in starting the bargaining process and will wield a little-used clause in the Fair Work Act to drag Public Service Minister Eric Abetz to the negotiating table.

But the Minister says the union's actions are unnecessary and regrettable and the government will publish its bargaining guidelines for departments on Friday, and he did not want to conduct the process through the media.

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The CPSU move is a dramatic escalation of the conflict developing between the union and the minister.

With enterprise agreements in 117 departments and agencies employing about 160,000 workers due to expire in June, the two sides have not even agreed on terms for the talks and unions have been increasingly vocal about the delay.

Department and agency bosses cannot start negotiations with their workforces and unions until the minister signs off on the long-awaited bargaining framework, setting out the basic principles the government wants enforced.

The unions have blamed the government for the delay but Senator Abetz has said the fault lies with the previous government, which he says failed to lay the groundwork for the complex negotiations.

Early drafts of the framework offered pay rises of 0 per cent unless workers agreed to trade away key employment conditions.

But The Canberra Times understands the finalised document, to be released on Friday, has a starting position of 1.5 to 2.5 per cent annual pay rises, well short of the 4 per cent in the log of claims the CPSU lodged late last year.

Under the Fair Work laws, a majority of workers at a workplace can force an employer to bargain, even if they are unwilling, with an instrument called a ''majority support determination''.

CPSU petitions are being circulated in three of the public service's most heavily unionised departments, Veterans Affairs, Employment, and Education, after union national secretary Nadine Flood said she and her colleagues had lost patience with the delays.

''We have taken this unusual step because this is an unusual situation with a government that is refusing to negotiate with its employees about their workplace agreements,'' Ms Flood said.

''Most employers agree to bargain with their employees without unions having to resort to this step.

''We have been asking the government for five months about bargaining and nothing has happened. Enough is enough.''

But Senator Abetz's office said it was exasperated with the CPSU's tactics in the lead-up to negotiations. The minister said the union should ''come to the negotiating table in good faith''.