Only President Ferdinand Marcos Jr. can decide whether or not the Philippines would rejoin the International Criminal Court which is now investigating his predecessor, former President Rodrigo Duterte, Senate President Juan Miguel "Migz" Zubiri said Tuesday.

"Whether to re-enter or to remain out of the jurisdiction of the ICC is not a decision we the senators make," Zubiri told reporters in a Viber message.

"It is the decision of the President of the Republic being the Chief foreign policy maker of our country," he added.

Earlier in the day, opposition Senator Risa Hontiveros filed a resolution urging the Marcos administration to cooperate with the ICC's investigation into Duterte's bloody drug war.

Hontiveros' resolution came after the president said his administration is looking into the country's possible return to the ICC.

"Should we return under the fold of the ICC? So that is again under study. So we'll just keep looking at it and see what our options are," Marcos said.

The Philippines withdrew its membership from the Rome Statute in March 2018 upon the order of then-president Rodrigo Duterte. The withdrawal took effect on 17 March 2019.

Marcos' predecessor, Duterte is accused of committing crimes against humanity before the ICC in relation to his bloody war on drugs that killed at least 7,000 people, according to government data, which was questioned by both local and international human rights groups, stressing that the actual figure is higher than the said numbers.

Zubiri noted that the president "alone makes that decision and everything else is just noise on whether we should join or not."

'Bring it on'

Senator Imee Marcos, likewise, said that the decision whether or not to rejoin the ICC belongs to the president, his brother, Marcos Jr.

"So they really want trouble? Well, PRRD [former president Rodrigo Roa Duterte] has said 'Bring it on!' But the decision to cooperate or not to is one for the Executive, and my brother, the President of the Philippines, has already made it clear that the ICC has no jurisdiction to conduct the probe. I share that view," Senator Marcos said.

Last week, the lawmaker downplayed House resolutions calling for government agencies to cooperate with the ICC's investigation against the Duterte administration's war on drugs.

Without naming who she is referring to, Senator Marcos lambasted individuals whom she said are advancing their political interests for the next elections.

"Those behind this have been very active in doing a show in the recent three or four weeks. I hope they feel pity for the Philippines," she said.

"We have so many problems. I hope they feel pity for the administration. They feel pity for the Filipinos who are struggling to survive their daily needs despite the higher cost of commodities. Not to mention Christmas is coming too," she added.