Philippine President Rodrigo Duterte has warned he may use his executive power to suspend a legal safeguard against arbitrary arrest and detention, and was willing to use drastic measures and even go to jail to make his war on drugs a success.

The former prosecutor, dubbed "the punisher" and elected on promises of a fierce campaign to stop crime and illicit drugs, said there were so many narcotics suspects on his wanted list that building cases one-by-one took too much time and manpower.

He was therefore considering suspending a writ of habeas corpus, which requires the state to justify arrests and detentions.

"I am the president. Of course I have the powers," he said at the launch of a foundation late on Friday.

"I can be ordered by the Supreme Court to stop it, but there are things that they cannot, and maybe, I will not, stop.

"I can go to jail. File all the charges that you can think of. But this country, in my time, will not deteriorate any further."

In the absence of the writ, police would be able to detain suspects without warrant and hold them for three days without charge.

According to the constitution, the president may "in case of invasion or rebellion, when the public safety requires it", suspend the writ for periods of up to 60 days. The same clause allows for martial law to be invoked, but Duterte said he would not do that.

The firebrand former city mayor has resolutely defended his drugs crackdown and chastised anyone who has voiced criticism or concern, among them the European Union, U.S. President Barack Obama and U.N. Secretary-General Ban Ki-moon.

Duterte's speech on Friday was not attended by media and his office issued a transcript of the remarks on Saturday.

Presidential Communications Secretary Martin Andanar said one of Duterte's reasons for considering the move was to go after people in government who were linked to the drugs trade.

"The list of the persons of interest, who are in government, is just too much," Andanar said in a text message.