President Rodrigo Duterte has warned of "radical changes" in the coming days as he vowed to use his emergency power to the hilt.

"I am warning you criminals, all of you. Those in the government, those outside. I will make the radical changes in the days to come," Duterte said in a press conference at the airport shortly after his arrival from South Korea on Tuesday night.

For government offices which could not be controlled despite his warnings from engaging in corruption, he said, "I will place you under the Office of the President. You will face me everyday."

Duterte said he was thankful he was given an opportunity to serve the country.

He said changes will be made, particularly on public order and security.

"There are simply too many crimes and too many - claiming to be this and that," he said.

Duterte said there was no big difference between martial law and a declaration of national emergency.

"So I've been warning all. I'm warning all including the human rights (groups), it's either we behave or we will have a serious problem again," he said.

Human rights groups have been critical of the government's bloody war on illegal drugs.

Duterte noted most of the concerns were about kidnappings and killings.

"Well, somehow, even with this meager emergency power, I will use it to the hilt and put things in order," he said.

Duterte did not say what he would do.

However, martial law is existing in Mindanao while the rest of the country is still under the declaration of a state of emergency.

Duterte has not yet lifted the proclamation he issued in September 2016, declaring a state of national emergency on account of lawless violence in the country.

He imposed the state of national emergency shortly after the bombing incident in a night market in Davao City on September 2, 2016, resulting to the death of 14 people and injury of 67 others. Celerina Monte/DMS