(2nd UPDATE) President Rodrigo Duterte has invited officials of the United Nations (UN) and European Union (EU) to conduct a probe on his war on drugs, amid concerns over the extra-judicial killings that have resulted from it.

“I’m inviting the United Nations, si Ban Ki-moon… I am inviting the EU, iyang pinakamahusay. Send the best lawyers of your town. Pati ang mga [UN] rapporteurs pumunta sila sa Pilipinas. I will write them a letter to invite them for an investigation,” Duterte said in a speech in Villanueva, Misamis Oriental.

[I’m inviting the United Nations, Ban Ki-moon… I am inviting the EU, the best of them. Send your best lawyers. The UN rapporteurs should also come here. I will write a letter to invite them for an investigation.]

Duterte, however, set a condition for the invitations--that UN and EU officials should give him a chance to air his side.

“In keeping with the time-honored principle of the right to be heard, matapos nila akong tanungin, tanungin ko sila. Isa-isahin ko sila in open forum… Tapos manood kayo, tingnan niyo kung paano ko lampasuhin ang mga yawa na iyan.”

[In keeping with the time-honored principle of the right to be heard, after they ask me questions, I will also ask them questions. I will ask them one by one in an open forum… You watch as I demolish them.]

Duterte has been accused of using vigilantes to kill criminals in his home city of Davao, where he served as mayor for over two decades.

Edgar Matobato, a self-confessed former member of the Davao Death Squad, told a Senate hearing that he killed on Duterte’s orders.

In his speech, Duterte denied ordering the killings, saying the deaths of suspected criminals were the handiwork of crime gangs and drug syndicates.

Duterte said when he faces UN and EU officials, he will ask them for details of the allegations.

“Ang una ko lang tanong sa rapporteur, 'I killed thousands, o what was the name of the first victim? What, where, and for what reasons? How was it done? What time was it?''' he said.

[My question to the rapporteur will be, 'If I killed thousands, what was the name of the first victim? What, where, and for what reasons? How was it done? What time was it?']

In another speech in Cagayan de Oro, Duterte said he has ordered Executive Secretary Salvador Medialdea to work on the invitation.

"I will write them a letter. I will furnish the press next week," he said.

Duterte issued this invitation in the wake of the call of his staunchest critic, Senator Leila de Lima, for the UN to hold its own investigation into the killings in the government’s war on drugs.

• READ: De Lima to UN: Probe Duterte drug war

Duterte earlier slammed the UN secretary-general and the EU for criticizing his war on drugs' impact on human rights.

• READ: 'F*** you,' Duterte tells European Union

Over 1,700 drug suspects have been killed since Duterte won the elections in May, based on monitoring by the ABS-CBN Investigative and Research Group.

A total of 1,002 people were killed in police operations and 569 killed by unidentified assailants from May 10 to September 21.