Mining firms in the Philippines voiced outrage Wednesday over government plans to cancel nearly one quarter of the nation's contracts, plus a permit to exploit one of the world's largest known copper deposits.

Environment Secretary Gina Lopez announced Tuesday she would cancel 75 of the nation's 311 mining contracts, as well as the environmental compliance certificate of the planned $5.9-billion Tampakan copper and gold project.

The Chamber of Mines of the Philippines said it would fight Lopez's decision, warning it threatened $22-billion worth of projects. The contracts are for projects in the pipeline but are not yet operating.

"She's out to kill the industry. We do not see a future for us under her," Ronald Recidoro, the chamber's vice president for legal and policy affairs, told AFP.

"Her announcement was bloody in all aspects."

Lopez, appointed by President Rodrigo Duterte last year, has railed against what she insists are the environmentally destructive and exploitative practises of local and foreign miners in the Philippines.

"Water is life. If you put at risk the water supply of the community there, you are putting at risk the quality of life of the people," Lopez said on Tuesday.

This month Lopez also ordered the closure of 23 existing mines and the suspension of five others, saying they illegally encroached on watersheds, leaked waste into rivers and destroyed trees.

The Philippines is the world's top supplier of nickel ore and main exporter to China, and the government actions have impacted global metal prices.

Lopez said Tuesday mining companies would be given seven days to explain before the cancellation of the 75 contracts were carried out.

However the mining industry has warned it will take all legal measures to fight Lopez's moves, which are widely expected to be brought before the Supreme Court.

Mining firms accused Lopez of breaching contracts and asked congress on Tuesday to reject her confirmation as environment secretary.

The Tampakan copper-gold project in the southern Philippines had already been stalled by regulation hurdles, including a local government ban on open-pit mining.

Recidoro warned Tuesday's announcement would be a huge blow for the local economy.

"This will lead to the loss of what will probably be the biggest employer in the area," Recidoro said.