MANILA - Justice Secretary Vitaliano Aguirre II said Friday he has ordered the National Bureau of Investigation (NBI) to look into an alleged destabilization plot against the administration involving opposition leaders.

The department order was released days after the justice chief publicly raised the possibility that some opposition leaders may be involved in the Marawi City attacks carried out by the terrorist Maute and Abu Sayyaf groups, said to be backed by the Islamic State.

Aguirre has drawn flak for making public accusations without verification.

• READ: 'Misquoted'? Aguirre recants statement against Marawi clans

"[T]he [NBI], through Director Dante A. Gierran, is hereby directed and granted authority to conduct investigation and case build-up over the alleged destabilization plot against the government of the Republic of the Philippines by some senators and other opposition leaders, and if evidence warrants, to file the appropriate cases against those who may be found liable," read Aguirre's Department Order No. 385, which also directs the bureau to conduct a case build-up.

The order had no other details, and did not name the personalities that Aguirre wants investigated. It also did not state what led the justice chief to issue the order.

The order bears the date June 7, 2017, the same day that Aguirre, in a press conference, bared receiving raw and unverified information about an alleged meeting in Marawi City among opposition Senators Bam Aquino and Antonio Trillanes IV, Magdalo party-list Rep. Gary Alejano, Aquino administration adviser for political affairs Ronald Llamas, and local leaders on May 2, three weeks before clashes began in Marawi City

Aguirre then said "it's probable, it's possible" that said meeting could have "sparked the terroristic acts in Marawi."

The Marawi attacks prompted President Rodrigo Duterte to declare martial law and suspend the privilege of the writ of habeas corpus in Mindanao.

"Hindi ko malaman why after they went there nagkagulo na after two weeks. They met with the people there, they met with several families there," Aguirre had told reporters on Wednesday.

Aguirre, however, later cleared Aquino, clarifying that "further verification" has established that the lawmaker "was not present in the alleged meeting of opposition leaders said to have been held in Marawi City on May 2, 2017."

• READ: Aguirre: Minority senators' meet with Marawi leaders could have sparked siege

Aguirre also apologized to the Alonto and Lucman clans in the city, whom he also mentioned to have met with the opposition leaders, explaining that "no member of both families ever met with Sen. Trillanes, Congressman Alejano, and Ronald Llamas."

Senators Grace Poe and Leila De Lima slammed what they called "fake news" coming from the justice secretary.

Poe, chairperson of the Senate Committee on Mass Media, said: "What makes it worse is when the Justice Secretary himself willingly exploits and amplifies such fake news like a troll without a modicum of effort to at least verify the same just to malign political opponents."

De Lima, detained on drug charges, called Aguirre the Duterte administration's "clown" and described the justice chief's statements as a "bungling accusation" against opposition members.

Aguirre insisted he was "unfortunately misquoted by some reporters."

During his June 7 press conference, Aguirre stressed that the information he received needed verification and suggested "government should look into" the alleged opposition meeting in Marawi.