At least 30 people were killed in shootouts between hundreds of tribal warriors in Papua New Guinea's highlands, police said Monday.

Police said the unrest started in August when "illegal miners" inflicted life-threatening injuries on a landowner in the Porgera Valley, home to one of Papua New Guinea's largest gold deposits.

Peace talks failed, and the situation spiraled into intense tribal fighting that saw 300 shots fired Sunday alone, according to police commander, Joseph Tondop.

Police said 30 men had been killed across the rival clans and hundreds of women and children displaced, with "many" homes burned to the ground.

Two officials were also killed while waiting for a lift home after work, said Tondop.

Police Commissioner David Manning said "lethal force" would be used to restore order in the hard-to-reach highlands region.

"Put simply, this means if you raise a weapon in a public place or to threaten another person, you will be shot," Manning said in a statement at the weekend.

"This deteriorating situation has been caused by illegal miners and illegal settlers who are victimizing traditional landowners and using violence to terrorize local communities."

Police said illegal miners from the Sakar clan had been squatting on land owned by their Piande rivals.

Alcohol sales have been banned and an overnight curfew is in place, added Manning, who vowed to remove the artisanal miners from the valley.

Tribal conflicts are a frequent occurrence in Papua New Guinea's highlands, but an influx of automatic weapons has made clashes deadlier.

The latest burst of fighting had been turbocharged by the presence of more than "100 high-powered weapons in the wrong hands," police said.

Security teams have been posted along the highway leading to the mine, using loudhailers to broadcast messages of peace.

'Stop the spiral'

The Porgera gold mine once accounted for around 10% of Papua New Guinea's yearly export earnings.

But recurrent flare-ups of tribal violence and a drawn out government takeover have slowed production in recent years.

Gunfights between rival clans living near the mine killed at least 17 in 2022.

And at least 26 people were killed, including 16 children, when three villages in East Sepik province were attacked earlier this year.

Pope Francis urged Papua New Guinea to "stop the spiral" of violence during a visit earlier this month.

"It is my particular hope that tribal violence will come to an end," he said.

"It causes many victims, prevents people from living in peace and hinders development."