The draft laws were given the green light in the lower house on Monday night, despite unions and crossbenchers fearing the trade deals will put the Australian government at risk of being sued by big businesses.

Opponents are also worried there is little evidence of the economic benefits the free trade deals will deliver.

Labor confirmed last week it would back the deals, but wanted Trade Minister Simon Birmingham to make a series of assurances, including that the agreements won't allow foreign workers to replace locals.

The minister wrote to the opposition on Monday, with Labor leader Anthony Albanese saying his commitment meant the opposition could safely back the laws in parliament.

"I'm convinced that overall these will be positive," he told the lower house.

Labor trade spokeswoman Madeleine King stressed the "enormous benefits" trade has brought to Australia, including job creation.

Trade tensions between the United States and China have also increased the significance of the new deals, Ms King said.

"We must ... diversify our export markets, lest we become a victim of the dispute between the two largest economies in the world."

Trade Minister Simon Birmingham welcomed Labor's support and said ratification of the agreements would boost export opportunities and deliver significant benefits for Australian farmers and businesses.

"These free trade agreements will open new doors and deliver wide-ranging benefits for Australian exporters from industries including agriculture, manufacturing, mining, education, tourism and financial services," Senator Birmingham said in a statement.

Unions aren't impressed with the concessions Labor has secured, saying there is no analysis that proves the deals will be lucrative for Australia nor a guarantee local jobs will be filled by locals first.

Under clauses in the agreements, the Australian government could also be sued if companies argue the new laws would reduce their profits, the Australian Council of Trade Unions says.

"These agreements are negotiated behind closed doors, and everything we know about them indicates that they are designed to benefit multinational companies, not Australian workers," ACTU president Michele O'Neil said.

Several crossbenchers also expressed concerns the deals could give big businesses too much power or lead to foreign workers being exploited.

"These agreements give more rights to big corporations than to governments and to workers," Greens MP Adam Bandt said.

"You're watching the corporate colonisation of your country," Queensland MP Bob Katter said.

The Greens failed to pass amendments that would address their concerns, while Labor failed to pass an amendment noting the concerns it had held about the bill.

Senator Birmingham expects the draft laws to clear the Senate by the end of the year.

Hong Kong and Peru have completed their ratification processes and it is expected Indonesia will complete its processes in a similar time frame to Australia.

Australian Associated Press