Construction, Forestry, Mining and Energy Union (CFMEU) organiser Dave Curtain raised the concerns in Wollongong this week while speaking about the alleged underpayment of 29 Chinese and Filipino men working in metal construction at the Manildra site in Bomaderry, most in the country on 457 visas.

The agreement would allow Chinese companies carrying out large infrastructure projects worth over $150 million to staff their projects with Chinese workers without testing the local job market.

"We've got rising unemployment, areas of high unemployment, why are we allowing the floodgates to be opened for workers from overseas when we've got more than enough people to staff the jobs here?" he said.

"We've got the workers here, we have the people, we've got the unemployed here, let's give them the opportunity to work."

While he conceded there could be exceptions for highly specialised jobs, Mr Curtain said he believed in most cases bringing in overseas labour was unnecessary.

He and fellow CFMEU organiser Dave Kelly met with the Australian representative of the Chia Tung Development Corporation, the company that employs 29 overseas workers allegedly paid as little as $1.75 an hour, in Wollongong this week.

The meeting raised issues about who had most responsibility for the workers, with Chia Tung Australia director and secretary Alan Sinclair telling the union his company had no control over the men's contracts, which were held by the Taiwanese-based Chia Tung Development Corporation.

Another meeting will be held on Tuesday at the Manildra Group site at Bomaderry and Mr Curtain said the union would be demanding the workers be given their legal entitlements.

"If it's not resolved satisfactorily on Tuesday it will be taken further, through the powers that be, the secretary of our union and our national office," he said.

"It will become political, I believe it should be anyway."

The Department of Foreign Affairs and Trade was asked for comment on the free trade agreement.