Philippine President Rodrigo Duterte has vowed that his campaign against illegal drugs will not ease despite mounting criticism over the rising death toll, calling on the nation to keep supporting him.

Duterte, in his annual State of the Nation address, before Congress, said that the illegal drug campaign was part of efforts to ensure peace and order in the country to encourage investment.

"I have learned that the economy surges only when there is peace and order in places where investors can pool their capital and expertise," the 72-year-old president said.

"That is why I have resolved that no matter how long it takes, the fight against illegal drugs will continue because that is the root cause of so much evil and so much suffering that weakens the social fabric and deters foreign investments from pouring in," he added.

The president also called on his critics not to trivialise his drugs war by demanding human rights.

Thousands of people have died since Duterte took office last year and ordered an unprecedented war on crime that has drawn global criticism for alleged human rights abuses.

The move, however, has been popular with many in the mainly Catholic nation.

Duterte also said he wanted all mineral resources extracted from the country to be processed domestically and, if possible, to stop exporting such commodities.

He said he would hold mining companies responsible for the clean-up and rehabilitation of areas damaged by mining.

He added that the government on Friday would draft a new law for the country's mining industry, which he said pays too little in tax and not enough in compensation for any environmental damage.

Criselda Yabes, a columnist, told Al Jazeera from Manila that there was not much change compared to when Duterte made his State of the Nation address last year.

"There has not been any signs of change in the country," she said.

"[The president] would generally find the prepared speech boring, deviate from the text and talk about anything under the sun," Yabes said, adding that most of the time people get confused during his speeches.

"You see Congress members clapping his every word and laughing at every joke he makes, demonstrating the state of the country."

Protests

Ahead of the address, several thousand left-wing protesters marched in the capital Manila with an effigy of Duterte to the House of Representatives to demand that he deliver on promises.

Riot police, without batons and shields to underscore a policy of maximum tolerance towards demonstrators, separated the protesters from a smaller group of Duterte supporters outside the heavily guarded building, where Duterte delivered the speech.

Inside the hall, left-wing legislators sought ingenious ways to protest. Representative Emmie de Jesus, who represents the Gabriela women's party-list group, wore native clothes with beadwork reading "Regular Jobs Now", a criticism of contractual work without benefits.

Another representative, Arlene Brosas, wore a black dress with a hand-painted message by a former political prisoner saying "No to Martial Law."

Duterte won congressional approval on Saturday for an extension of martial law in the south to deal with the siege of Marawi city by an armed group, the worst crisis he has faced since taking power last year.