Australian Prime Minister Malcolm Fraser today proclaimed the toughest antiunion legislation in the country's history and led his government into an all-out confrontation with the powerful trade union movement.

The law, called the Commonwealth Employes Act, was passed by the Federal Parliament two years ago, but Fraser withheld putting it into force until today, although he had frequently threatened to do so.

The act gives the federal government or the managers of government-owned authorities such as the postal service, the telephone system and the national railways the power to suspend without pay or fire government workers in an industrial dispute.

Immediately after it was proclaimed - a simple process of taping a copy of the act to the window of the government publisher's headquarters bookshop - the government began suspending hundreds of workers in the national telephone system, called Telecom.

Today's decision provoked widespread protests and the threats of a national strike. Robert Hawke, Australia's most powerful trade unionist and president of the Australian Council of Trade Unions, called an emergency meeting of its executive board early next week.

Hawke, Australia's nearest equivalent to AFL-CIO leader George Meany, strongly attacked the legislation, claiming it violated rights laid down by the International Labor Organization, of which Australia is a member. He accused the government of refusing his offer to defuse the issue.

Although not formally on strike, the Telecom technicians have imposed bans on the national telephone and telecommunications network for the past 3 1/2 weeks.

By today less than 30 percent of the nation's telephone, telex and TV network system was operating. The technicians, who earn between $200 and $350 a week, were demanding a pay increase of at least $25 a week.

The technicians' union wanted to negotiate with the Telecom management in a form of collective bargaining relatively rare in Australia. The government virtually directed Telecom's management to have the case decided by the federal arbitration commission, where the government expected a much smaller increase or none at all to be awarded.

The conservative prime minister today accused Hawke of coming into the battle too late and not being willing to settle the issue a week ago.

In addition to leading the most powerful trade union body in Australia, Hawke, 50, is eager to enter politics and could attempt to enter Parliament later this year.

He has said that if he enters politics it would be to seek leadership of the opposition Labor Party and eventually challenge Fraser for the Prime minister's job.

The government-union confrontation came in the middle of the worst industrial turmoil Australia has seen for many years. Much of the eastern seaboard is just recovering from four weeks of enforced gas rationing caused by a strike that closed the nation's largest refinery.

After years of union-management squabbling, the postal workers are severely restricting mail in Sydney, the largest city, and have virtually stopped all foreign mail movements for nearly a month.

Transport unions have closed down state rail, streetcar and bus services several times in recent weeks, and disputes on the rich iron-ore minefields in the northwest have virtually stopped export of the metal.

More than 500,000 federal civil service employes are covered by today's law. Any of them now can be suspended in any industrial dispute. Although the government has not moved yet to use the law's most Draconian provision, the act also gives it power to dismiss any of its employes suspended during an industrial dispute - a tough penalty in a public service where length of tenure guarantees higher pension and retirement payments and seniority.

With the prime minister declaring his government has no intention of backing down, Australia faces the prospect that massive union retaliation could close down most industry and commerce.