MANILA, Philippines -- The Philippines' new president said Friday he "will go to the extreme" in his battle to end crime and cleanse the police force of wrongdoers within six months, but pledged he won't become a dictator.

Rodrigo Duterte said in a speech to the police that he is not afraid of being impeached by Congress while fighting crime and assured officers he would protect them if they kill large numbers of people while cracking down on lawlessness. The crackdown, he warned, will extend to the 170,000-strong police force.

"I am warning you, I will be harsh," Duterte said. "I will go to the extreme."

As a former prosecutor who charged erring policemen and soldiers in his southern city of Davao for years, Duterte said he knows how to detect corrupt military and police personnel, some of whom are involved in the illegal drug trade. The records of all policemen linked to crimes will be reviewed, he said.

"Do your duty," Duterte said. "If in the process you kill 1,000 persons because you were doing your duty ... I will protect you, and if they will try to impeach me, I will hurry up the process and we go out of the service together."

Duterte was inaugurated Thursday in austere rites at Manila's Malacanan presidential palace after winning May 9 elections on a promise to eradicate crime and corruption in three to six months, an ambitious plan that has sparked alarm. Human rights watchdogs have warned Duterte against resorting to shortcuts and abuses.

Duterte said he would go hard on crime, but "I do not want to be a dictator."

In recent weeks, dozens of suspected drug dealers have been killed, either in reported gunbattles with police or under mysterious circumstances. On Friday, 10 drug dealers were killed separately in gunfights with police in Bulacan province north of Manila as the nationwide crackdown commenced, according to police.

Duterte expressed particular anger against convicted drug traffickers who continue to deal secretly in methamphetamines at the national penitentiary in metropolitan Manila. He suggested a potentially bloody crackdown was imminent at the heavily guarded prison.

"You're putting the government to shame. You're slapping us. You should count hours, I don't like days," Duterte said.

Hundreds of drug addicts and pushers have surrendered to authorities in recent weeks, concerned they would be killed in the crackdown, officials said.

Duterte witnessed the official appointment of his national police and military chiefs in separate ceremonies and ordered them to combine their forces to fight criminals.

Aside from anti-crime efforts, Duterte said he would pursue peace talks with communist and Muslim rebels, and announced he would meet next week with the leaders of the Moro Islamic Liberation Front, the largest Muslim rebel group in the country.

Duterte will travel to southern Jolo island to meet Nur Misuari, a leader of another Muslim rebel group. He also expects talks soon with Jose Maria Sison, the founding chairman of the communist party who plans to return home soon after living in exile in Europe for about three decades.

"We cannot fight forever," Duterte said. "My job is to bring peace, but, hand in hand, I must also bring order in my country."