Thousands of Australians rallied in the southern city of Melbourne Wednesday in a protest against new labor laws they claim make it easier to fire workers.

Melbourne, headquarters of Australia's trade union movement, was brought to a halt by the protest marking three months since parliament passed the laws.

The changes reduce restrictions on employers firing staff unfairly, critics say. They also say the laws are driving down wages.

Kim Beazley, who leads the union-backed opposition Labor Party, vowed to repeal the laws if he becomes prime minister at elections next year.

He estimated the crowd at 150,000 people.

"This is a battle for ordinary Australian life," Beazley told the rally. "It's also a battle for basic dignity in the workplace."

The rally in Melbourne, Australia's second largest city after Sydney, was expected to be the largest in a day of protest action across the nation.

Workplace Relations Minister Kevin Andrews said the protests were the product of a fear campaign by militant unions.