Clive Palmer says he will challenge the decision of an international tribunal to dismiss his claim for $305bn in compensation from the commonwealth government, by appealing to a court in Switzerland.

On Saturday the attorney general, Michelle Rowland, announced that the permanent court of arbitration, in The Hague, the Netherlands, had ruled against the Queensland mining magnate.

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The investor-state arbitral tribunal, which mediates free trade disputes between foreign investors and the states in which they invest, dismissed Palmer’s claim that a decision blocking a Pilbara mining proposal violated international law. It ordered him to pay more than $13m, Rowland said. The decision has not yet been published on the court’s website.

“Mr Palmer is not a ‘foreign investor’ and is not entitled to any benefits under Australia’s free trade and investment agreements,” Rowland said on Saturday.

On Sunday, Palmer posted a statement on social media.

“Mr Palmer said that he and his legal team would challenge the tribunal’s judgment, ensuring the matter is tested in a forum in which the lawful arguments of his case are properly heard,” the statement on X said.

“He said the federal supreme court of Switzerland would be the next step in the journey to achieve justice in the matter, hopeful of the final arbiter taking an opposite view to that of the tribunal”.

The legal battle has already lasted a decade.

Palmer brought the lawsuit on behalf of his Singaporean investment company Zeph Investments, claiming damages worth almost $US200bn ($A300bn) after a mining proposal in Western Australia’s Pilbara region was blocked.

Palmer was challenging a series of decisions that prevented him developing the Balmoral South iron ore mine, in the Pilbara region. His company Minerology claimed the right to mine 1bn tonnes of magnetite iron ore. It is reportedly the world’s largest reserve of the mineral; work has been under way on the mine since 2008.

Palmer claimed that Western Australia’s decision refusing to allow the mine a permit breached the 2010 Asean-Australian-New Zealand free trade agreement. The WA government passed a law exempting itself from the lawsuit in 2020, which Palmer challenged to the high court, without success.

International law expert Alvin Yap, from the university of Western Australia, said Palmer was able to challenge the decision in a Swiss court because Switzerland is the “seat” of the tribunal, which uses that country’s authority to effect its decisions. The challenge will be heard under Swiss law.

If Palmer wins there, Yap said, the court could overrule the decision and send it back to the tribunal or order a new tribunal hear the case.

“The Swiss court can’t order the Australian government to pay compensation to Mr Palmer,” Yap said.

Palmer’s company, Zeph Investments, now has four claims under the process against the Australian government including this one. He is also suing for $120bn in compensation as a result of Queensland government decisions blocking construction of two mines and a coal-fired power station.

The other three claims were suspended last year while the Pilbara case was decided.

The investor state dispute process (ISDS) has been criticised by environmentalists and others as a threat to the sovereignty of elected governments, and their decisions to protect the environment.

Australian Fair Trade and Investment Network convener, Patricia Ranald, said it was not clear if all four claims had been dismissed.

“Palmer’s last three cases join a growing global list of ISDS cases from fossil fuel companies against government decisions to reduce carbon emissions. A recent United Nations Report concluded that ISDS is a “major obstacle” to government action on climate change,” she said.

She said the federal government should accelerate a promised review of Australia’s ISDS commitments.