MANILA, Philippines (AP) — Philippine police said Wednesday they have arrested a suspected Chinese drug trafficker and seized one of the largest amounts of illegal drugs this year.

More than 370 kilograms (815 pounds) of methamphetamine with an estimated street value of more than 2.5 billion pesos ($49 million) was discovered in the suburban Makati city apartment of Liu Chao after he was arrested, police said.

Two Filipinos who allegedly worked as Liu’s drug dealers were arrested Tuesday night with 17 kilograms (37 pounds) more of methamphetamine, a highly addictive stimulant, in a separate police raid in Las Pinas city in the Manila metropolis, national police spokesman Brig. Gen. Bernard Banac said.

Police said they have been monitoring Liu for two weeks and he tried to escape Tuesday night after sensing that he was making a deal with a police officer pretending to be a drug buyer. He was caught and police later found the methamphetamine concealed in Chinese tea packs in his apartment, police officer in charge Lt. Gen. Archie Francisco Gamboa told reporters.

Investigators were trying to determine where the drugs, locally called “shabu,” came from.

President Rodrigo Duterte launched a crackdown on illegal drugs after taking office in 2016 that has killed more than 6,000 mostly poor drug suspects in reported clashes with police.

The killings have alarmed Western governments, U.N. human rights experts and rights groups and sparked two complaints of crimes against humanity which are being examined by the International Criminal Court.

Duterte withdrew the Philippines from the ICC after questioning its power to investigate his government’s anti-drug campaign. An ICC prosecutor has said she will continue examining the complaints.

Duterte, a former mayor and prosecutor known for his extra-tough approach to fighting crime, has denied condoning extrajudicial killings but has openly threatened drug traffickers with death. He has pledged to press on with the crackdown until the end of his six-year term.

Tuesday’s drug seizures were the latest indication that the illegal drug problem persists despite Duterte’s crackdown. In March, law enforcers confiscated more than 160 kilograms (350 pounds) of methamphetamine also concealed in tea wrappers in raids in an upscale residential enclave and outside a shopping mall in metropolitan Manila. Three Chinese citizens and a Chinese-Filipino man were arrested in the raids in Alabang village in the Manila metropolis.

Philippine officials say the tea wrappers used to conceal the drugs are similar to ones found in drug seizures in Malaysia, Thailand and Myanmar and indicate an international syndicate is behind the trafficking.