A group of civil society organisations has demanded that Apple Inc remove from its app store games it said violated the tech firm's guidelines and promoted violence and killings commonplace in the Philippines' war on drugs.

The group named several apps featuring characters based on Philippines President Rodrigo Duterte and his national police chief, Ronaldo "Bato" dela Rosa, who engage criminals in gun battles and fistfights.

"These games valorise and normalise the emerging tyranny of Duterte's presidency and his government's disregard for human rights principles," the Asian Network of People who Use Drugs (ANPUD) said in an open letter to Apple's Chief Executive Officer, Tim Cook.

Apple did not immediately respond to a request for comment from Reuters.

The group listed 131 organisations from numerous countries as supportive of the Oct 10 complaint to Apple, among them groups working on human rights, youth and drug policy reform.

They urged Apple to issue an apology for hosting such "insensitive content".

Thousands of Filipinos have been killed in Duterte's 15-month-old war on drugs, a campaign that has caused international alarm. Human rights groups say state-sponsored executions are taking place, an assertion the authorities vehemently reject.

The group said games such as "Fighting Crime 2", "Duterte knows Kung Fu", "Duterte Running Man Challenge", "Tsip Bato" and "Duterte Vs Zombies" "might seem harmless and fun" but were offensive and distasteful because in reality, murder and impunity had prevailed.

"Duterte Running Man Challenge" was not available for download on Friday, and three of the app developers could not be reached for comment.

Ben Joseph Banta, a managing partner of Ranida Games, which developed "Tsip Bato", said the game sought to discourage drug use with the use of banner messages opposing drugs that were visible to players.

"The aim of our game is not to promote violence," Banta said in an emailed response, adding that it featured "supplemental digital content against the use of illegal drugs."

"We understand the human rights groups and we're very much open to make changes in the game in order to remove the stigma that the game is promoting violence," he said.