Metro Manila (CNN Philippines, April 14) — Senator Richard Gordon will not entertain calls to resume the investigation into the multibillion-peso illegal drug shipment which slipped through the Bureau of Customs, after presidential son Paolo Duterte and former Presidential Economic Adviser Michael Yang were implicated in the drug case.

Gordon, chairman the Senate Blue Ribbon Committee, said in a Sunday statement their accusers must submit sworn statements and evidence to bolster their allegations.

“Hindi ko pwedeng buksang muli ang imbestigasyon at magsagawa ng hearing base lamang sa mga alegasyon. Magpapatawag lang ako ulit ng hearing kapag haharap sa'min si Acierto at Alyas Bikoy at kapag nagsumite ng kanilang sinumpaang salaysay kakabit ang matitibay na ebidensya,” he was quoted saying.

[Translation: I cannot open the investigation and hold hearings based on allegations. I will call for a hearing anew if Acierto and Alyas Bikoy face us and submit sworn statements with strong evidence.]

On April 4, Senate Minority Leader Franklin Drilon on Thursday called for the resumption of the drug smuggling probe to look into accusations against President Rodrigo Duterte's son and Agriculture Undersecretary Waldo Carpio--who were tagged in a viral video by a certain "Alias Bikoy."

READ: Paolo Duterte links Trillanes to video on his alleged drug smuggling

Former PSSupt. Eduardo Acierto, who was implicated in the smuggling of shabu concealed inside magnetic lifters, has accused Yang of involvement in the illegal drugs operation in the country.

“Hindi pwedeng, itatago mo lang ang mukha mo at gagawa ka ng alegasyon tapos iimbestigahin ko na. Lalo na ngayong election time,” he said.

[Translation: You cannot hide your face and make allegations, and expect me to investigate the matter. Especially since it's election season.]

READ: Duterte asks military, police why Acierto is still alive

Gordon added opposition senators were given sufficient time during the hearings, to present their witnesses and evidence to prove their allegations against the first family and their friends.