The Philippines' national police chief said on Tuesday that about 300 police officers were suspected to be involved in the illegal narcotics trade and would soon be removed and charged in court if convicted.

Director-General Ronald dela Rosa said nearly 300 officers were on a suspected list of selling drugs confiscated in raids. The officers were also accused of protecting syndicates involved in the manufacture and distribution of narcotics.

He also told a Senate, an inquiry conducted by Senator Leila de Limaa, a critic of President Rodrigo Duterte, that there was no declared policy to kill drug users and pushers.

He said many people have been killed so far during a crackdown on illegal drugs, but all of those killings were not drug-related. Some of those were due to enmity or robbery. However, all of those killings were still being investigated to find out the reason.

"Not all deaths under investigation are drug-related," dela Rosa told Reuters.

The United States said it was "deeply concerned" by the reports of the extrajudicial killings. The State Department urged Duterte's government to abide by human rights norms.