The deaths from June 16 to 20 brought to 93 the total number of drug suspects killed since the start of the year, according to police.
Police stepped up the campaign against illegal drugs because Duterte has stressed it will be a key focus of his administration, said Chief Superintendent Wilben Mayor, the national police spokesman.
"Because of this focus, our personnel have been very aggressive," he said. "It's the number one priority of our incoming president."
An anti-crime group expressed alarm over what appears to be an "overzealous" attempt by the police to make a good impression on the incoming president.
Dante Jimenez, president of the Volunteers Against Crime and Corruption, warned that some police officers allegedly involved in illegal drug trafficking could actually be covering their tracks by eliminating their assets.
"We welcome all drug syndicates to be wiped out from the face of the earth. They are the source of the land," he said. "But we don't want an anarchy like this."
Jimenez said the fear was that most of the suspects killed were small-time pushers, while the drug lords and protectors remained free.
Mayor said the national police have launched investigations into recent operations to determine the circumstances surrounding the deaths of the suspects and to ensure that protocol was followed.
- DPA