Fortescue Metals Group chair Andrew Forrest told businessmen gathered in Tasmania on Wednesday that the revised mining tax being pushed forward by the Labor-led government of Prime Minister Julia Gillard only favoured Australia's big three mining firms.

Mr Forrest noted that the government only negotiated with BHP Billiton, Rio Tinto and Xstrata, which gave smaller companies the impression that the federal government deliberately left out other resource players.

The FMG head said that as a result of the selective mining tax discussion held by the government with the three giant firms, the resource industry absorbed an unstable financial environment in which banks became wary of pouring investments in proposed mining projects.

Also present on the Devonport breakfast meeting of mining executives was Grange Resources local chief Wayne Bould who lamented that the Labor government was not providing sufficient information on the proposed tax measures.

Mr Bould asserted that further details must be furnished by the federal government on the planned minerals resource rent tax in order for the mining companies to determine its possible effects on their businesses.

Ms Gillard earlier decided to postpone its promised MRRT dialogues with junior miners until after the August 21 elections amidst Grange's calls on the government to reconsider the proposed tax's framework, which the company claimed could endanger jobs at its north-west mining operation.

The Devonport visit of Mr Forrest was reportedly organised by Tasmania's Liberal Party but the FMG head was quick to clarify that his meet with fellow executives was purely business and he is not campaigning for any change of the government.