MANILA--A former Philippine opposition senator accused ex-President Rodrigo Duterte of plundering state coffers in a criminal complaint filed Friday, alleging that he conspired with an aide to award government infrastructure contracts worth millions of dollars to cronies.

Filed with the Department of Justice in Manila, the accusation adds to the former president’s legal worries, which include an investigation by the International Criminal Court into allegations of crimes against humanity over the widespread killings of suspects during Duterte's crackdown on illegal drugs.

Former Sen. Antonio Trillanes IV said two construction companies, owned by the father and brother of longtime Duterte aide and now Sen. Christopher Lawrence Go, received more than 100 government construction contracts worth at least 6.6 billion pesos ($114 million) from 2007 to 2018 in the southern city of Davao, while Duterte was mayor and vice mayor and after he became president in 2016. Neither company had the resources or manpower to handle large-scale infrastructure construction, Trillanes said.

Go said he has not seen the complaint but denied the allegations against him and Duterte.

“What I can assure everyone is I have not benefitted, and my family has not benefitted from my being in government,” Go said in a statement to reporters. “Even if you ask around, my relatives could not approach me — even my own father and half-brother — to get help in getting any project or government contract.”

Duterte did not immediately comment, but he has previously denied any wrongdoing in office.

Trillanes accused Duterte, Go and the relatives who owned the two companies of plunder.

Under Philippine law, the crime of plunder is committed when a government official acquires ill-gotten wealth of 50 million pesos ($862,000) or more from government funds through corrupt acts in combination with family or associates. It’s punishable by life in prison. The government can also seize illegally acquired wealth or properties after a final conviction.

Go, “in conspiracy with Mr. Duterte, used his position, authority and influence to corner billions worth of government projects in favor of his father and brother, thus, unduly enriching himself and the members of his immediate family,” Trillanes said. "Now is the perfect time to make them accountable.” He added, without elaborating, that the former president would face more lawsuits in the future.

Trillanes, an anti-corruption advocate who served as senator from 2007 to 2019, was one of Duterte’s most vocal critics. Trillanes also initiated a complaint against Duterte over the widespread killings under the former president’s deadly campaign against illegal drugs that sparked a still-ongoing investigation by the International Criminal Court.

Government prosecutors will conduct their own investigation before deciding whether to indict Duterte and the others accused in a process that could take months or years.

Duterte, 79, was a longtime mayor and vice mayor of Davao before rising to the presidency on a promise to rapidly rid his poverty-plagued Southeast Asian country of corruption and illegal drugs — both of which he's acknowledged failing to accomplish.

One of Asia’s most unorthodox recent leaders, Duterte's six-year presidency was marked by expletives-laced outbursts and high-profile efforts to nurture cozy ties with Chinese President Xi Jingping and Russian leader Vladimir Putin while openly lambasting U.S. and European leaders.

Duterte, a former government prosecutor and legislator, launched police-enforced crackdowns against illegal drugs when he served as mayor and vice mayor to his daughter, Sara Duterte, in Davao city, and later as president. Those campaigns killed more than 6,000 mostly minor suspects. The campaign was unprecedented in its scale and lethality in recent Philippine history and drew alarm worldwide.

Duterte and his top police officials denied authorizing extra-judicial killings under the campaigns, but he openly threatened drug traffickers with death and encouraged policemen to shoot drug suspects if they violently resisted arrest.