Labor is trying to adjust Australia’s free trade agreement with China, but the big unions say they have not gone far enough.

The China Free Trade Agreement has been criticised from the unionist side of politics over fears that it will let companies bring in workers with reduced accreditation, skills and language requirements.

The Opposition is now trying to force amendments that mean employers have to advertise jobs locally before looking overseas.

The ALP is also seeking for the minimum wage for people on 457 visas to be increased, and that higher skills tests be imposed.

Opposition Leader Bill Shorten says the Turnbull Government has agreed in good faith to look at the changes in related legislation — not the deal itself.

The Australian Council of Trade Unions (ACTU) says its political arm has not reached for enough to protect local jobs from a flood of foreign workers.

“There are still major gaps for us with the China free trade agreement and we don't think these amendments to the migration bill will fix all of the problems,” ACTU president Ged Kearney said at a union gathering this week.

“So the changes to the Migration Act do not cover all our concerns.”

The ACTU has set up dozens of local forums around Australia to challenge Coalition MPs to debate.

“I think until we're absolutely sure that our concerns are covered off we'll continue to campaign around this,” Ms Kearney said after Labor's announcement on Tuesday.

“Given that there are still concerns, we will continue to have a conversation with our members and the Australian people about our concerns that remain.”

Australian Industry Group chief executive Innes Willox said additional red tape - in the form of new tests Labor suggests - would weigh down business growth.

“If the Government and the Opposition come to an agreement around labour market testing — that that not be any more onerous than the current labour market testing provisions already are - we don't find that labour market testing is necessary,” Mr Willox said.

“It's costly [and] these are often in areas where business already knows there are labour shortages.”