Australia's union movement is launching a national campaign to highlight the plight of foreign workers employed on 457 visas.

It comes as the Federal Government recently announced moves to crack down on the visa system.

The Australian Council of Trade Unions (ACTU) says it is gathering evidence on the misuse of the foreign worker scheme.

It says the treatment of some foreign workers is tantamount to slavery.

ACTU secretary, Dave Oliver, says in one case a Filipino sandblaster was forced to do menial jobs at his employer's house.

"[He] was made to clean out office toilets, he was made to clean the bosses house, he had to go over and mow the boss' son's lawn," he said.

Mr Oliver says when the man complained he was sacked and has since been deported back to the Philippines.

The ACTU has launched a national hotline for foreign workers to report ill-treatment by employers.