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.