Labor has defended its support for a major trade deal which sparked internal tensions and angered the union movement.

The federal opposition is backing Trans-Pacific Partnership legislation, despite concerns over lack of labour market testing and provisions which could see foreign companies sue the government.

The bill, which will pass with Labor’s support, was debated in the Senate on Monday.

On the same day, Labor’s trade spokesman Jason Clare introduced a private bill to parliament’s lower house to put more safeguards in place for future trade agreements.

Mr Clare said the move would prohibit clauses which allow foreign companies to sue the government and protect public services.

“It will fix many of the existing problems with trade agreements and make sure the ones we sign up to in the future are better and fairer,” Mr Clare told parliament.

Opposition foreign affairs spokeswoman Penny Wong noted Labor’s concerns with the TPP, but said the strategic benefits of signing up to the deal were compelling.

“This is not the agreement we would have signed. The government could have done more and should have done more to protect the rights of Australian workers,” Senator Wong said.

A Shorten Labor government would try to change aspects of the deal if elected at the next election.

The Australian Council of Trade Unions maintains its opposition to the TPP but backed Labor’s new trade policy outlined in Mr Clare’s private bill.

“This will change the way our country does trade and who that trade benefits,” ACTU president Michele O’Neil said.

Centre Alliance will try to amend TPP legislation to remove investor-state dispute settlement (ISDS) provisions before the deal comes into effect.

It will also mandate labour market testing before foreign workers can be employed in Australia.

If those amendments are defeated, the minor party will try to insert a sunset clause repealing the legislation if bilateral side letters removing ISDS and labour market provisions are not exchanged by the start of 2020.

“The Labor Party are committing a fraud on their union comrades. They are committing a fraud on their supporter base,” Centre Alliance senator Rex Patrick said.

The Greens and One Nation are also opposed to the TPP.

“It’s a bad deal because it hands over extraordinary power to corporations and takes it off sovereign governments,” Greens leader Richard Di Natale said.