The clan killings, some of them depicted in gory videos posted on social media, resumed after a period of relative calm in an area of the Pacific Island state’s mountainous Enga province, said the region’s police commander George Kakas.
The toll could rise “much higher”, he warned.
“The number is 150 but we are still on recovery efforts for bodies in the bush,” Kakas said.
The violence broke out between two clans and escalated, sucking in other tribes and mercenaries from the district and beyond, the police chief said.
“Tribes are interconnected,” he added. “They include more people and it makes the fights bigger.”
Tribal clashes, often sparked by territorial disputes and theft accusations, have long troubled Enga.
The recent fighting was most heavily concentrated in the volatile Wapenamanda district, which had been peaceful for months, Kakas said.
About 170 people were killed in Enga province over several days during similar clashes that occurred around national elections last July, he added.
Videos on social media in the past month have shown cheering young clansmen brandishing axes, machetes, and firearms, such as AK-47 and M16 rifles.
One video published in August showed naked, mutilated corpses of three suspected mercenaries being dragged behind a utility vehicle in Wapenamanda district.
Prime Minister James Marape denounced it at the time as “jungle justice” but said it also showed that locals were fed up with “hired gunmen” taking part in tribal conflict.
‘Just there for money’
It was one of 15 graphic videos and photos seen on social media by AFP since last month.
PNG’s Royal Constabulary commissioner David Manning said police must be ready to use lethal force “where this is required and reasonable”.
Kakas, who oversaw the notoriously violent 2017 general election and moved to Enga one month before the 2022 general election, said mercenaries posed a new challenge.
Mercenaries are “not restricted by traditions or culture. They’re just there for money,” he said.
He described the hired guns as “restless young men” and “high school dropouts”, while some were also “village strongmen” from other parts of the island.
Tribal fighters could be ruthless in dealing with mercenaries, the police chief said.
“This is why they did this to those mercenaries, why they videoed it for everyone to see. To show everyone that they have no respect for them,” he said.
Mutilations of enemy corpses and the use of mercenaries showed an erosion of traditions, said Maho Laveil, Pacific analyst at the Sydney-based Lowy Institute.
“You’ve got a huge youth bulge, high unemployment issues,” Laveil told AFP.
Those who get jobs end up in the highlands’ lucrative marijuana plantations, he said.
“Most firearms follow the drug trade coming in from Indonesia,” Laveil said.
Marijuana from the highlands flows into PNG’s Western Province, which neighbours Indonesia’s West Papua, he said.
Laveil said remote communities were also more distant and less trustful of government.