PORT MORESBY: Papua New Guinea's head of government labeled a mass tribal killing in the country's highlands an act of "domestic terrorism" on Tuesday, as he pledged tougher measures to tackle mounting "lawlessness."

Prime Minister James Marape told parliament that a clash between rival tribal fighters that killed dozens of people near the village of Wapenamanda would prompt a raft of reforms to combat "domestic terrorism."

With citizens horrified by gruesome images of hacked and bloodied bodies piled on a road, and his country's international reputation in tatters, Marape insisted that his government would act.

"We know that the No. 1 threat facing us is lawlessness," he told lawmakers. "The economic growth and everything else that's happening will be totally redundant" without security, he said.

Police, government and local officials put the number of those killed in the attack at between 49 and 64, but the toll looks set to increase, as bodies continue to be found in nearby bushland.

The area has seen regular tit-for-tat tribal attacks for decades, with each revenge raid or ambush bringing a new cycle of violence.

Marape urged those close to the victims of the latest round of bloodshed not to take matters into their own hands.

"I want to encourage our youth out there, at no time must you proceed to another tribal land," he said.

Similar calls by previous governments have generally been ignored.

Marape, under pressure after recent unrelated riots in major cities, said new antiterrorism laws would soon be introduced to parliament.

The laws would criminalize terror financing and incitement, provide police with enhanced surveillance powers and establish a "special policing zone" across the highlands, police officials said.

The premier also rejected opposition calls to fire the country's police commissioner.

"We have been changing police commissioners as we've been changing our underwear," he said, insisting a rotating cast of police leaders in recent years had destabilized the force.