Energy giant ExxonMobil​ has not paid a cent in corporate income tax in Australia in at least two years, despite reaping more than $18 billion from the nation's natural resources, according to three of the company's workplace unions.

Tax campaigners accuse the company of cashing in on Australia's soaring gas prices, but avoiding paying tax on its profits by sending much of its money to a network of offshore companies, some based in notorious tax havens.

Credit:Michael Nagle

The company dismissed the unions' claims as "misinformation" and said it paid state and federal royalties on its Australian operations as well petroleum resource rent tax and corporate tax.

But in Victoria, where ExxonMobil runs the giant Esso Longford gas plant supplying much of the east coast market, the state government wants an investigation, saying Australians expect a fair return from companies profiting from the nation's natural resources.