Harry Roque told reporters
Thursday the ICC's Office of the Prosecutor informed Philippines officials they were conducting a preliminary inquiry into whether an investigation is needed.
"The President has said that he also welcomes this preliminary examination because he is sick and tired of being accused of the commission of crimes against humanity," Roque said.
Duterte sees an ICC examination as an opportunity to rebut allegations against him, Roque said, adding the ICC move was a waste of time and resources, pushed by enemies of the President in order to embarrass him.
The ICC "investigates and, where warranted, tries individuals charged with the gravest crimes of concern to the international community: genocide, war crimes, crimes against humanity and the crime of aggression," according to its website
In a statement
, Fatou Bensouda, the ICC's top prosecutor, confirmed she had opened a preliminary examination into the situation in the Philippines which "will analyze crimes allegedly committed ... in the context of the 'war on drugs' campaign."
"While some of such killings have reportedly occurred in the context of clashes between or within gangs, it is alleged that many of the reported incidents involved extra-judicial killings in the course of police anti-drug operations," she said.
Rights groups have long accused Duterte of gross human rights violations in his anti-drug campaign, which Human Rights Watch estimates
has claimed the lives of 12,000 people since June 2016. According to the Philippines government, around 3,900 people have been killed in the drug war.
Amnesty International said in October
that the campaign of police and extrajudicial killings "may constitute crimes against humanity."
the rights group warned "police have been allowed to operate in a culture of almost total impunity," adding that "all perpetrators, including those in positions of command, must be held to account."
Bloody drug war
According to CNN Philippines
, the ICC began looking into Duterte's drug war after lawyer Jude Sabio filed a complaint in April 2017.
In a statement Thursday, Sabio said he was "elated and vindicated" by the ICC's move, which he said was a "prelude to formal criminal investigation" of Duterte.
Sabio is the lawyer of
former hitman Edgar Matobato, who in late 2016 accused Duterte of overseeing a campaign of extrajudicial killings
when he was mayor of the southern Philippines city of Davao.
"Our work was to kill criminals like drug pushers, rapists, snatchers," Matobato said of the Davao Death Squad (DDS) of which he was a member. "Those were the people we killed every day."
The self-proclaimed head of the DDS, Arturo Lascanas, has also accused Duterte of overseeing the group's deadly work
, saying members received money from the then-mayor in exchange for killings of not only criminals but also of Duterte's enemies in politics and the media.
The Philippines government has denied both men's accounts, calling Lascanas' testimony a "fabrication."
While killings have dropped from their heights in the months after Duterte took office, he said in his State of the Union address in July that he would "hound (drug dealers) to the very gates of hell."
Roque defended the drug war Thursday as "an exercise of police power."
"It cannot be characterized as an attack against civilian populations ... It is a lawful use of force," he said, predicting the ICC probe "will not go beyond preliminary examination."
The ICC, intended as the world's "court of last resort,"
is a controversial body. Not all states are a party to it, including the US, Russia and South Africa, and it has been criticized
for being overly focused on developing countries, particularly African nations.