But the giant Department of Human Services has returned the union’s fire, accusing the Community and Public Sector Union of making $1 billion worth of demands from its new enterprise agreement.

DHS’s plan to keep its 35,000 public servants at their desks for an extra six minutes each day will net the government $104 million of work each year, but without a pay rise on the table.

The working hours push is part of an aggressive assault on conditions of workers during the enterprise bargaining process at the behemoth department which runs Centrelink, Medicare and the Child Support Agency.

As well as the longer working hours, DHS bureaucrats face the loss of overtime payments, a crackdown on leave entitlements, losing the right to be consulted on work rosters and a tougher ''performance management'' regime.

But a departmental spokesman told The Canberra Times the “ideas are simply the current proposals, and are still being actively discussed”.

The CPSU, the department’s main union, describes the department’s plan as a “shocker” and is warning DHS’s 35,000 public servants to brace for fresh attack on their wages when the departmental bosses unveil their pay offer.

CPSU deputy national president Lisa Newman, has told her members that the bosses’ plan to add six minutes to the department’s working day of 7.5 hours would add up to big gains for the federal government.

''This would result in an additional 30 minutes work per week, an additional 3.46 days’ work per year and an approximate 1.36 per cent pay cut for all DHS workers,'' union official told DHS workers.

''This means working an extra six minutes a day will deliver the government $104 million dollars in additional working hours but will not deliver you a fair and reasonable pay rise.''

Ms Newman also accused DHS of dragging its feet on making a pay offer, saying public servants were effectively on a pay freeze while negotiations continued after the government banned back-pay on new workplace agreements.

''They know that every week that goes past represents a pay freeze for their Australian Public Service workforce,'' Ms Newman said.

“It’s hard to imagine a pay offer that could possibly compensate DHS workers for the cuts the department has proposed. However, until we know what their pay offer is, no one can make an informed decision.”

CPSU National Secretary Nadine Flood backed her union official, sayng DHS staffers were already putting in extra hours at work.

''DHS workers have copped hundreds of millions of dollars in cuts, which have led to massive workload pressures and increased client aggression,'' Ms Flood said.

''Now they're being told none of that extra work counts as productivity in bargaining.''

But DHS Human Services general manager Hank Jongen said his department was putting in more effort than any other public service agency into striking a deal with its workers, despite operating in a difficult financial environment.

''There have been 13 days of bargaining, more than any other agency, and the department is committed to putting the agreement to the vote as soon as possible,'' Mr Jongen said.

''For the department, every 1 per cent pay increase per year equates to around $181 million over the three-year life of the new agreement.

”We have costed some elements of the union’s log of claims for our department at over $1 billion dollars over the life of the new agreement. This is unaffordable.”