Australia imposes mining tax after two-year battle

* Tax on profits will affect about 30 companies

* Victory for Prime Minister Gillard's struggling minority government

* Association of smaller miners says tax will discourage investment

* Opposition has said it will repeal tax if it wins power

By James Grubel

CANBERRA, March 19 (Reuters) - Australia's parliament passed laws for a new 30 percent tax on iron ore and coal mine profits on Monday after a bruising two-year battle with mining companies, in a major victory for Prime Minister Julia Gillard and her struggling minority government.

The tax will affect about 30 companies, including global miners BHP Billiton , Rio Tinto and Xstrata, and aims to raise about A$10.6 billion ($11.2 billion) in its first three years.

"This is indeed an historic day for economic reform, and an historic day for a fair go in Australia," Treasurer Wayne Swan told parliament.

The tax, which is being closely watched by other resource-rich countries, is designed to spread the benefits of Australia's resources boom to other sections of the economy by funding a cut in the company tax rate, higher payments into pension funds, and A$6 billion of infrastructure spending. Continued...