Claiming that the mining tax being pushed by Prime Minister Julia Gillard is discriminatory, Fortescue Minerals Group (FMG) chief executive Andrew Forrest said on Tuesday that he is prepared to challenge the measure's legality in the Australian High Court.

According to BusinessDay, Forrest stressed that the minerals resource rent tax (MRRT) proposed by the Gillard government heavily favors the country's giant mining firms such as BHP Billiton, Rio Tinto and Xstrata, which he insisted should not have been the case as the three companies can very well afford to cover the additional expenses entailed in the new tax initiative.

The federal government aims to commence implementation of the MRRT by July next year and the legislation required for the new tax policy has reached the draft stage. The new tax was formulated to replace the earlier planned resources super profits tax (RSPT) that the mining industry strongly opposed.

To save the new tax program, Ms Gillard forged a deal with BHP, Rio and Xstrata last year, paving the way for the gradual gravitation of support for the MRRT.

However, Forrest, along with other smaller mining players, called on the government to review the proposed mining tax provisions, which has been touted by Federal Treasurer Wayne Swan as an effective tool that will balance Australia's budget issues with its projected income of more than $7 billion over the first two years of its operation.

Meanwhile, Resources Minister Martin Ferguson told ABC that Forrest's criticism on MRRT was not based at all on its constitutionality but on the benefits that the measures will deliver on his mining operations.

ABC quoted Ferguson as saying that the FMG boss "wants the Australian mining tax system to be designed to suit the personal circumstances of his company."

The minister reminded Forrest that the Gillard government has designed the MRRT to ensure that the Australian community will benefit most from the huge income that it will generate.

Ferguson also wondered aloud why Forrest and his cohorts greeted with silence the recent directive issued by the West Australian government, which will led to spiking royalties being slapped on iron ore mining operators in the region.