Tony Abbot promises to rescind PM Julia Gillard's new tax on mining if the Coalition wins the elections despite mining giants supporting the new deal.

The leader of the Opposition has announced the upcoming federal elections would be based on the tax issues and claimed that the battle lines are all set.

"Labor supports a great big new tax on mining - the Coalition doesn't," Mr. Abbott said in Sydney, repeating the line he said to dispute Labor's seemingly emission trading plan "It's as simple as that."

Mr. Abbott's argument came as the junior miners complained about the new mining tax scheme, when they were left of the negotiations with the big mining firms.

The Australian government earlier today has dropped intentions for imposing 40 per cent tax on thriving mining profits.

The new 30 per cent tax will apply to the coal and iron ore mining industries, Australia's largest exports, and will start on 2012.

However, Mr. Abbott commented that the mining firms were "effectively negotiating with a gun at their heads, and that's not a situation they should ever have been put into".

Joe Hockey, spokesman of the Opposition's Treasury, said the new tax would inevitably affect and have "consequences for more than 300 companies that were not at the negotiating table".