MANILA - Six witnesses have surfaced to prove Senator Leila de Lima's alleged role in the proliferation of drugs inside the New Bilibid Prison (NBP), Justice Secretary Vitaliano Aguirre said Thursday.

Vitaliano said the Department of Justice (DOJ) is in the process of taking the affidavits of six witnesses, including NBP guards, inmates and former friends of De Lima.

"Bumabaha ang information, volunteered information ha," he said.

Justice Sec.Vitaliano Aguirre on evidence vs. Sen. Leila De Lima: Bumabaha ang impormasyon. | via @adrianayalin pic.twitter.com/zhNmpmCDoR — ABS-CBN News (@ABSCBNNews) August 25, 2016

President Duterte himself earlier accused De Lima of receiving campaign funds from drug lords at the NBP, through her former driver, who is also her alleged lover, when she was still justice secretary.

Duterte: Driver was De Lima’s link to detained drug lords

Duterte on Thursday also tagged De Lima and six other officials in a matrix that shows their supposed involvement in the narcotics trade.

READ: Duterte's 'drugs matrix' tags De Lima, other

But Aguirre said the DOJ investigation will not focus on De Lima or any specific personality alone, but rather on why drugs proliferated inside the NBP under the Aquino administration.

The DOJ, he said, has also discovered several bank accounts where supposed drug funds were deposited, although their direct link with De Lima has yet to be established.

"Yung pinag-depositohan hindi sa pangalan niya basta sinabi nila dun dineposito sa account na 'yun," said Aguirre. (The bank accounts were not under de Lima's name but witnesses said drug money is deposited there.)

He added that the evidence against De Lima will be used in a House inquiry on the alleged rampant illegal activities at the state penitentiary.

De Lima, he said, may be charged with graft and drug-related grafts once the DOJ verifies the information against her.

The senator has denied the charges against her and branded Duterte's drug matrix as "laughable."

READ: Furious de Lima slams Duterte 'drug matrix': Is this a joke?