Officials said the deaths occurred in Hela province -- a rugged region in the west of the country -- when rival tribes apparently clashed over control of local gold deposits in the mineral-rich soil.

Highland clans have fought each other in Papua New Guinea for centuries, but an influx of automatic weapons has made clashes more deadly and escalated the cycle of violence.

Hela provincial administrator William Bando told AFP on Wednesday that the death toll could rise.

"We are still waiting for today's brief from our officials on the ground," he said, calling for at least 100 police to be deployed to reinforce some 40 local officers.

The incident has shocked both the country and recently appointed Prime Minister James Marape, whose constituency includes the district where the killings occurred.

He vowed more security deployments and warned the perpetrators "your time is up".

"Today is one of the saddest day of my life," he said in a statement. "Many children and mothers innocently murdered in Munima and Karida villages of my electorate."

In the Karida attack, six women and eight children -- as well as two pregnant women and their unborn children -- were hacked and shot to death in a 30-minute rampage.

Local health worker Pills Kolo said it was hard to recognise some of the body parts, and posted images of remains bundled together with mosquito nets used as makeshift body bags.

Images provided by local police showed the corpses of two children of school age, one with severe head injuries.

Local media reported the attack appeared to related to the ambush and murder of six people the day before.

Marape blamed the violence on three related warlords who have been fighting against the Tagali tribe over local gold deposits.

"Gun-toting criminals, your time is up," Marape said. "Learn from what I will do to criminals who killed innocent people, I am not afraid to use strongest measures in law on you."

He noted that the death penalty was "already a law".

Tribal clashes are a frequent occurrence in Papua New Guinea's highlands, where old rivalries prompted by rape or theft, or disputes over tribal boundaries or resources, often prompt violence.

But this is the most serious incident in years and the government -- which has only 40 police and 16 soldiers in the area according to Bando -- is struggling to respond.

In nearby Enga province, a similar surge in violence prompted the establishment of a makeshift military garrison and the deployment of a company of around 100 government soldiers under the command of a Sandhurst-trained major.

But even those forces lack the resources to tackle difficult terrain.

Bando said 35 officers currently providing security for a nearby ExxonMobil gas project "should be released to assist those on the ground to ensure safety for the families".

Marape has not yet provided details of planned security deployments to the area, but appeared exasperated by the current resources available.

"How can a province of 400,000 people function with policing law and order with under 60 policemen, and occasional operational military and police that does no more than band-aid maintenance," he said.