Opposition Leader Tony Abbott has tried to shift the focus of the workplace relations debate by challenging Labor MPs to support legislation aimed at cracking down on corruption within unions.

Mr Abbott has introduced a private members bill that would increase the penalties on union officials found guilty of misusing their members' funds, following allegations involving the Health Services Union.

"It is high time that we put the interests of workers ahead of the interests of union officials, and that is what the Coalition intends to do," he told Parliament.

"The challenge for members opposite will be: do they back the interests of... workers, or do they back the interests of (union) officials?

"Unless the Government is prepared to show it's serious by entertaining the bill that I am putting before the Parliament, what will be exposed is that the real friends of the workers of this country are on this side of the Parliament."

Mr Abbott had previously flagged plans to introduce the legislation.

His move to bring on debate comes a day after the Prime Minister sought to put industrial relations policy at the forefront of this week's parliamentary agenda.

Workplace Relations Minister Bill Shorten says it is clear the Coalition does not want the debate.

"Whenever we talk about workplace relations, someone in central bunker Liberal headquarters presses the alarm button, and they say 'quick, we'd better get out and bash some unions'," he told Parliament.

"I love it when Tony Abbott... reminds everyone, as he did today, he's the workers' best friend.

"With friends like him, you don't need enemies."

Julia Gillard announced changes to workplace laws yesterday, with the aim of increasing the number of employees who will be able to request flexible working arrangements.

The changes would apply to people aged over 55, those who have finished parental leave, people with a disability or carer's responsibilities, those experiencing domestic violence, and parents of school-aged children.

"There is a lot of women who, whilst they have the right to take parental leave, when they come back it's just impossible to resume their existing employment," Mr Shorten told earlier today.

"Industrial relations in the modern world... is not just about an argument of slashing conditions.

"It's about understanding that we need to boost participation rates, it's about understanding that people are having families later in life, it's about understanding that there's a lot of financial pressures on two-income households when one person has to go back and be the carer."

He says the legislation will be an extension to the existing right to request flexible working arrangements, although employers will not be obliged to agree to the request.

Greens deputy leader Adam Bandt says the proposed changes lack substance, arguing employees should be able to appeal against a refusal to Fair Work Australia.

"An employee who asks for time off to look after someone who's suffering from domestic violence, or to look after their kid, or to look after their grandparent, deserves the right to a fair hearing from their employer and the ability to go somewhere if their employer just refuses them outright," Mr Bandt told reporters in Canberra.

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The Government is this week also planning to outline legislative amendments to help protect workers against roster changes.

Business groups have expressed concern about the Government's workplace plans, warning it will put many businesses offside.

"We already have a very regulated Labor market and deep frustration within the business community about our capacity to manage all of that regulation in a very competitive world," Peter Anderson from the Australian Chamber of Commerce and Industry told ABC News 24.

"It looks like the Government's going to over-regulate and that's going to deepen the rift between the Government and the business community on industrial relations issues."

Labor is hoping its pitch to "modern families" on work-life balance will flush out some more detail from the Coalition about its plans for the workplace.

Liberal frontbencher Kevin Andrews says the Coalition will carefully examine the Government's proposed changes, and will put forward its own policy before the election.

"We will come forward with a sensible industrial relations policy," Mr Andrews told ABC News 24.

"We've listened to the Australian people. They made it clear to us that they didn't appreciate some aspects of what WorkChoices was on about, and so that's something of the past."

Some Coalition MPs want to make substantial changes to the Fair Work Act, although Mr Abbott has said that any amendments will be "careful, cautious (and) prudent".