Chevron, the US oil giant behind Australia's biggest liquefied natural gas project, has been hit with claims its tax affairs are a "rort".

But the company insists it is the victim of "misinformation" peddled by unions and the media.

Two of Chevron's most senior executives mounted a defence of the company's behaviour at a Senate hearing in Sydney amid persistent criticism over its tax contribution in Australia.

A Federal Court judge last month slapped Chevron with a $269 million bill for unpaid taxes in Australia between 2004 and 2008. The company announced on Tuesday that it will appeal the ruling to the High Court.

Chevron's vice president and general tax counsel, Sandy Macfarlane, who flew from the US to front the Senate's corporate tax avoidance committee, described the case that led to the court findings against the company as merely "a difference of view" with the Australian Tax Office.

Mr Macfarlane said he was particularly aggrieved by a report last week in the Australian Financial Review that revealed the company paid just $248 in tax on an estimated $1.7 billion Australian profit rerouted to the low-tax US state of Delaware as interest on a loan.

"It's one of the reasons I'm here. There has been a lot of misinformation going around," Mr Macfarlane said.

He insisted "there is no profit" – meaning the $1.7 billion was never taxable – and the loan was "eliminated" between Chevron's US and Australian entities .

"What that [story] does is completely ignore the federal treatment, it's only looking at what was filed in Delaware. Delaware is a bit of a red herring. Delaware is one of the 50 states [of America]. Everything in Delaware is subject to US tax," he said.

"All these arrangements are in accordance with the law."

Mr Macfarlane said the $248 was likely to be a "filing fee in Delaware" rather than tax paid on the $1.7 billion transfer out of Australia.

Senators not convinced

But the explanation did not wash with senators from both sides of politics who have spent months grilling executives from multinationals, including Apple, Google and Uber.

"We have spent a year trying to find Australia's biggest tax dodger and we've found it," said Labor senator Sam Dastyari.

"It's Chevron. It continues what we have seen time and time again. The structures created by Chevron with its own internal structures are a rort. They've always been a rort."

Liberal senator Sean Edwards blasted the company for its convenient use of US and Australian dollar transactions to "minimise tax".

Company defends transparency

Roy Krzywosinski, the managing director of Chevron Australia, said the company had been "open and transparent" in its dealing with the ATO and disputed the characterisation of his company as a tax avoider.

"Chevron did not engage in any illegal activity or tax avoidance," he said.

He confirmed the company was again being audited over its new funding arrangements from 2009 to 2013.

Chevron confirmed it had 200 companies registered in the low-tax American state of Delaware and 200 in the tax haven of Bermuda.

Chevron Australia Transport, a Chevron-owned company that has a stake in a shipping company, is in turn owned by Chevron Australia Transport Bermuda.

Mr Krzywosinski said most international shipping companies are owned through Bermuda and the country had a remarkable maritime safety record.

He described the company's investment in the Gorgon and Wheatstone projects of the Western Australian coast as the biggest capital investment in Australia "ever", giving jobs to 150,000 workers and $338 billion to the government in tax and other revenues, according to research done for the company.

"[That] $350 billion will buy a lot of hospitals and purchase a lot of schools," he said.

Union blamed for misinformation

He blamed the union-backed International Transport Workers Federation for spreading misinformation through its submission to the Senate inquiry.

The $US54 billion Gorgon project in Western Australia – jointly owned by Chevron, Shell and ExxonMobil – ran $US17 billion over budget.

When its approval was announced in 2007, Chevron and then WA treasurer Eric Ripper promised that Gorgon alone would deliver $17 billion in PRRT and company income tax.

The company even claimed the project would deliver so much tax that it could facilitate personal income tax cuts for ordinary Australians.