MANILA - The proposed Senate investigation into the estate tax liabilities of the Marcos family is not politically motivated and is of national interest, Sen. Aquilino "Koko" Pimentel III said Tuesday.

The investigation is in aid of legislation and the public could benefit from the Marcoses' P203 billion estate tax liabilities, according to the senator.

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"They ignored everything, now it’s P203 billion. Di ba tayo interesado doon as a nation? Ngayong marami nang naghihirap, naghahanap ng pondo, saan mangggaling ang ayuda? P100 billion ang hinahanap na ayuda, P203 billion ito," he told ANC's Headstart.

"Di rin naman insolvent ang estate na nagkakautang eh. It's a matter of national interest made all the more interesting because the survey frontrunner belongs to the family who is inheriting the estate of the deceased Ferdinand Marcos. Kailangan ipaliwanag bakit ganun kalaki ang estate."

The Marcoses should have been able to pay the basic estate tax amount that the Supreme Court decided with finality in 1999 which is P23 billion, Pimentel said. The amount has since ballooned to P203 billion due to interest, charges and surcharges.

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"Ang estimate ng BIR (Bureau of Internal Revenue) ang estate na ito has more than P100 billion, that's why P23 billion ang tax due. This kind of an estate should be able to afford lawyers that would be able to fight for the rights of the estate," he said.

"The BIR started with the P100 billion. Mas malaki ang estate kesa sa estate tax. We can be able to at least collect the estate tax amount."

Former and current BIR officials and administrators of the Marcos estate must be called to the Senate hearing, Pimentel said.

"I want to find out what are the weaknesses in our tax laws, in the National Internal Revenue Code. How come the BIR cannot seem to collect such a world-record amount which the BIR already won in a final decision," he said.

Pimentel is the son of former Senate President Aquilino "Nene" Pimentel Jr, who was arrested several times under the Marcos dictatorship and co-founded PDP-Laban to oppose the strongman.

A faction of PDP-Laban led by Energy Secretary Alfonso Cusi has endorsed Ferdinand "Bongbong" Marcos Jr.'s presidential bid.

Pimentel, who leads a faction of PDP-Laban that supports Sen. Manny Pacquiao's presidential bid, said he was "glad we had this schism in the party" which led to "automatic cleansing."

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"They believe in personality-based politics. If they leave us, then we are blessed," he said.

"The status quo was that I and Sen. Manny were leading the PDP-Laban and Secretary General Melvin Matibag filed a case against us asking Comelec that they should be the ones recognized. They're the ones filing a case to change the status quo."

Pacquiao still has a "narrow path to victory," according to Pimentel, who said he has "lost trust" in election surveys.

"We will respect his decision and if he says right now there is no way he will withdraw, we are with him. We never foresaw he would be withdrawing when we joined him from day 1," he said.