Roque said then Duterte would welcome the probe because "he is sick and exhausted of being accused.(by) the commission of crimes against humanity".
The President's decision came following the ICC's decision to open a preliminary examination into the alleged crimes committed in his bloody war on illegal drugs. "The statement made by the UN High Commissioner for Human Rights is being treated very seriously".
Last year, Amnesty International said the alleged extrajudicial killings by police "may constitute crimes against humanity".
Victoria Tauli-Corpuz, a Philippine national and the UN's special rapporteur on the rights of indigenous peoples, said in a telephone interview that she is "concerned" about the Philippine government's attempt to list her and about 600 others as "terrorists".
"Rather than attacking human rights bodies and human rights defenders, we urge the government to display honest commitment to transparency and the rule of law by allowing unhampered investigations to take place", the commission said.
The preliminary examination is not an investigation, the ICC said, but a process to see if there is basis to proceed with an investigation.
"It is apparent that the ICC is being utilised as a political tool against the Philippines", he said.
Duterte conceded that human rights investigators would likely be angered by his advice, but he insisted silence in response to their questions is legal under Philippine constitutional law.More news: Federer, Cilic, Del Potro advance in Indian Wells, Djokovic out
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He said when the Philippines became a signatory to the Rome Statute, it was on the assumption that the worldwide accepted principles of justice in relation to its constitutional requirement on due process would be upheld.
It said the withdrawal from the Rome Statue was due to the "baseless, unprecedented and outrageous attacks on my person as well as against my administration" by United Nations officials, and what he said was an attempt by the ICC prosecutor to seek jurisdiction over him "in violation of due process and presumption of innocence".
Duterte added that the crimes attributed to him were neither war crimes nor genocide.
Police say they have killed about 4,100 drug dealers in shootouts during official operations.
He noted that the treaty has not yet been published in the Official Gazette or in newspapers even after its ratification in 2011.
Philippine officials had initially said in February that the country was ready to cooperate but asked for fairness.
Last week, he said the ICC would "not in a million years" have jurisdiction to indict him.
Also, Duterte said the ICC could not subject the Philippine President to any investigation during his tenure due to the doctrine of immunity from lawsuit while in office.
Duterte has long denied the accusations of human rights abuses and contends the drug issue is one for domestic law enforcement.