The world's biggest trade union has accused US energy giant Chevron of profit shifting to minimise its taxes in Australia.

A report by the International Transport Workers Federation has accused Chevron of hiding more than $US35 billion in untaxed revenue offshore.

In response, Chevron denied it had breached tax laws in the countries in which it operates.

Chevron is building the Gorgon and Wheatstone gas projects off the northern coast of Western Australia, projects worth $84 billion.

The federation also said Chevron had at least 600 shell companies in tax havens like Bermuda and Delaware and that its tax returns had been challenged in the US and other countries.

The report said the US government had not approved Chevron's tax filings for more than seven years.

Chevron is currently in dispute with the Australian Taxation Office (ATO) over a tax bill, with the ATO alleging the company used a complex scheme of related-company loans to cut its bill by more than $250 million.

The matter is before the Federal Court.

A Chevron spokesperson said the company complied with local laws in all the countries it operates in, including Australia, and had paid more than $3 billion in taxes in Australia between 2010 to 2014.

"Chevron abides by a stringent code of business ethics, under which we comply with all applicable laws and regulations in the countries in which we operate, including Australia," the spokesperson said.

"As one of the Australia's largest investors, Chevron will pay its fair share of tax and, through the Chevron-led Gorgon and Wheatstone Projects, Australia will continue to enjoy the associated economic benefits over the life of the projects."

Chevron said the Gorgon and Wheatstone projects had created 17,000 jobs.

The company paid nearly $US12 billion in taxes globally in 2014 with an effective tax rate of 38.1 per cent.