More than 500 people heard welfare, church, Aboriginal and political representatives express their concerns about the IR agenda, which could see workplace conditions become less secure and negotiable.

The rally, organised by the Ballarat Trades and Labour Council, coincided with Prime Minister Howard's assurances that the new laws would not see workers negotiate their lunch breaks for more money or work public holidays without extra pay.

It also followed the High Court's decision on Friday to let the government continue its taxpayer-funded advertising spree promoting the changes.

Australian Council of Social Services president Andrew McCallum warned the crowd about the government's tactic of incremental change.

"This government does what the community tolerates in the first instance. When that is passed, it brings in more radical changes slowly. Ten years down the track you realise that your rights have gone."

Mr McCallum said the reforms would mostly affect Australia's 2.4 million people living in poverty.

"We will become like America - a great underclass of working poor. We may have a zero unemployment rate but people will be working three to four jobs to keep above the poverty line," he said.

Maurice Blackman and Cashman legal firm representative Dan McGlade gave an employer's view.

He said people were living in fantasy land if they believed Mr Howard's assertion that the proposed Australian Workplace Agreement would liberate workers.

He said school leavers in their first jobs would not have an equal playing field to bargain with their employers.

"These reforms will take us back to the 19th century, back to master and servant," he said.

Ballarat MHR Catherine King agreed.

She said the overhaul was the Government's "race to the bottom" and would hurt lower paid people in low skilled jobs.

Ballarat Catholic Diocesan representative Gerry Leahy said the church was against the changes.

He said they would impinge on people's dignity and right to fair workplace conditions.

Aboriginal Elder Ted Lovett continued the message, saying that ordinary people needed to be treated as equally as the wealthy.

Premier Steve Bracks sent a message of support.

He said the government, which has full control of the Senate, had betrayed voter's trust by failing to tell them about the reforms at the last election.