Philippine president Rodrigo Duterte wants all minerals extracted in his country to be processed domestically as part of a crackdown on miners that could hit dozens of Australian companies.

In a state of the nation address, Mr Duterte vowed to tax miners "to the death" if damage to the Philippines' environment persisted.

"If possible we shall put a stop to the extraction and exportation of our mineral resources ... for processing abroad and importing them back to the Philippines in the form of consumer goods at prices twice or thrice the value of the raw materials," he said.

Analysts say the comments will further shatter the confidence of mining companies to explore for minerals in the island-nation, which according to the Australian government's Austrade has untapped deposits worth an estimated $A840 billion.

More than 40 Australian mining equipment and technology providers operate in the Philippines, the world's biggest supplier of nickel ore and among the top producers of copper and gold.

Australian company OceanaGold operates Didipio, one of the world's lowest cost gold mines, 270 kilometres north of Manila.

Earlier this year, then environment minister Regina Lopez, a staunch environmentalist and ally of Mr Duterte, ordered the suspension or closure of almost 30 of the country's mines, including Didipio, as part of a campaign to fight environmental degradation.

But Melbourne-headquartered OceanaGold appealed directly to Mr Duterte to prevent its closure of Didipio, which employs 1800 workers.

At the time Australian Peter Wallace, a leading business consultant in Manila, said the crackdown had prompted a number of overseas mining companies to abandon plans for the Philippines.

Ms Lopez was replaced in May after Philippine lawmakers rejected her appointment.

In his address, Mr Duterte called on "industrialists, investors, commercial barons to put up factories and manufacturing establishments right here in the Philippines to process our raw materials into finished products."

The Philippines has only four mineral processing plans, two for gold and two for nickel.

Most of the minerals extracted in the country are shipped abroad unprocessed.

Mr Duterte said he is making protection of the environment a priority, saying miners have "considerably neglected their duty".

"You have to come up with a substitute, either spend to restore the virginity of the source or I will tax you to death," he said.

Previous governments in the Philippines called for more domestic processing of raw materials but the country's parliament never enacted laws to enforce it.

Mr Duterte, a bombastic former mayor of the southern city of Davao, took office in June last year vowing to crackdown on drugs and crime.

In the address he promised to press on with his controversial drug war that has claimed the lives of thousands of mostly poor Filipinos.

With agencies