MANILA - Opposition senatorial bets have urged Ombudsman Samuel Martires to investigate President Rodrigo Duterte and other administration officials in light of allegations of a former police official linking presidential adviser Michael Yang to illegal drugs.

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Asked in the middle of their campaign sortie in Cebu province, the opposition candidates said the Ombudsman could undertake a motu proprio investigation or a probe done on its own initiative on statements made by former police official Eduardo Acierto.

Otso Diretso senatorial bet former Quezon Rep. Erin Tañada said that while the President is immune from criminal suit, results of the investigation of the Ombudsman may be passed to the House of Representatives.

“Whatever the results the Ombudsman may have may be recommended to the House for impeachment proceedings,” Tañada said.

Election lawyer Romulo Macalintal said if Malacañang itself is "compromised," then the whole administration's credibility is tarnished.

“'Yung allegations and revelations ni Mr. Acierto puts a potential dagger to the credibility of the war on drugs,” Florin Hilbay, a former solicitor general, said.

Peace advocate Samira Gutoc, meanwhile, pleaded for a halt in the anti-narcotics campaign, saying the victims of police house-to-house anti-drug operation Oplan Tokhang in Cebu "feel the pain."

Acierto, a former anti-drug police official earlier linked to the drug trade, had surfaced and linked Yang, a businessman, and one Allan Lim to operations of a large shabu laboratory busted in Davao City in 2004.

Duterte had denied in October 2018 that Yang was one of his economic advisers. In the same month, he cleared the Chinese businessman from allegations of links to the drug trade.

Presidential Presidential Spokesperson Salvador Panelo later admitted that the businessman was indeed one of the President's "economic consultants."

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