"I would like to issue a warning on Monday … I will declare all your positions, all throughout the country vacant. I still hear corruption," the former provincial mayor said in a televised news conference on Sunday.

Mr Duterte also warned that some appointed government officials should prepare to be sent to Jolo, a far-flung island in the southern Philippines that is a base for Islamist militants and kidnappers.

"You will enjoy the ambience (and) enjoy the environment … you have only yourselves to blame for corruption," he said. "Until now, in my provincial visits, I still hear corruption being committed by people, especially in the regulatory agencies."

The directive spares officials of his cabinet and career officials.

When asked why cabinet officials are not included, Mr Duterte said: "It is too early for them to be corrupted."

Mr Duterte, the tough-talking former mayor of Davao, was swept into office at elections in May promising to eliminate illegal drugs in the country within months.

More than 650 people have been killed since June in battles with police officers and another 889 others have been killed by vigilantes who often leave cardboard signs declaring their victims to be drug pushers.

More than 600,000 drug dealers and pushers have turned themselves in to police to avoid being killed.

The killings have been condemned by human rights groups, many politicians and the Catholic Church.

In a speech last week Mr Duterte appeared to back away from his election pledge to end drugs trafficking by any means necessary, cautioning police to refrain from using deadly force "if you're not in danger of losing your life".

For weeks horrific photos of victims have been splashed across the pages of Philippines newspapers.

But Mr Duterte did not call for an end to the killings, as opinion polls show his popularity remaining high.

"The fight against drugs will continue unrelenting until we have destroyed the apparatus operating in the entire country," he said.

Mr Duterte has refused to allow United Nations investigators to probe the extrajudicial killings.

"The … so-called investigations by third parties are an objectionable interference in the household affairs of a nation whose citizens welcome the change that the president and his people-friendly policies and programs have set in place," said presidential spokesman Ernesto Abella.

Speaking on Sunday, Mr Duterte even suggested he might leave the world body and invite China and other nations to form a new one saying the UN could not fulfil its own mandate but was "worrying about the bones of criminals piling up".

Asked about the possible consequences of his comments, he said: "What is ... repercussions? I don't give a s--- to them."

Among dozens of cases of extrajudicial killings, The New York Times reports a 49-year-old father and his 28-year-old son who smoked shabu, a cheap form of methamphetamine, were severely beaten after being taken to a police station from a Manila slum.

Police claimed the two tried to escape by seizing an officer's gun. But a forensic examination found the men had been incapacitated by the beatings before they were shot at least three times, including in the head.

Mr Duterte has  launched a series of scathing personal attacks on Senator Leila de Lima, the former Philippines justice secretary, who is overseeing a potentially explosive Senate committee hearing into the killings.

"It's foul. It's character assassination," Senator de Lima told reporters, adding she will not call off the hearings, which begin on Monday.

The Philippines Commission on Human Rights is also investigating the killings.

with Reuters