Communities have taken matters into their own hands in the "absence of law and order policing", Papua New Guinea's Police Minister says, following the burial of the victims of a brutal tribal massacre in the country's Highlands this week.

Key points: PNG's Police Minister says "these situations are real" and "getting worse"

PNG's Police Minister says "these situations are real" and "getting worse" The United Nations condemns the violence, calling for immediate intervention

The United Nations condemns the violence, calling for immediate intervention PM describes the killers as "warlords", adding it's unlikely they will be held accountable

Earlier this week, at least 18 people — mostly women and young children — were slaughtered in the Highlands' Hela province, including unborn babies of two women who were believed to have been pregnant.

"People need to realise that as our institutions are collapsing, the viciousness on a community level is getting worse," Police Minister Bryan Kramer said today.

Locals volunteered through the night to provide a proper and dignified burial for the victims. ( Facebook: Rocky Robert Wakinda )

"These situations are real, they are happening, and there are increasing occurrences of them."

The outbreak of violence is the most recent of a decades-old tribal conflict in the Pacific nation's mountainous and remote Highlands region.

Mr Kramer said he will be travelling to Tari — the capital of the Tari-Pori District in Hela province — to personally assess the killings under the direction of Prime Minister James Marape.

The motive behind the killings remains unknown, though officials suggest it could be an act of retribution for another recent tribal dispute that left seven dead.

Mr Marape described the killers as "warlords" and said it is unlikely they will ever be held accountable by the province's small police presence, which, in addition to an influx of high-powered weapons into PNG's Highlands, community groups have blamed as emboldening tribal violence in the region.

There are currently only some 60 police officers in the vast and remote province of 400,000 people.

Children buried together following 'senseless killing'

Wooden coffins were prepared by locals for the victims. ( Facebook: Rocky Robert Wakinda )

Last night, more than 15 women and children were given burials by locals at Karida village.

It is reported the children were buried together in one grave, while their mothers and older children were buried separately.

The United Nations has released a statement condemning the massacre in Hela province and called for immediate intervention to bring the perpetrators to justice.

"We denounce in the strongest terms these heinous fatal attacks that show a ruthless disregard for human rights and the rule of law," said David Mcloughlin, acting UN resident coordinator.

"The senseless killing of people, including children, who have a fundamental right to be safe and protected from violence, is unacceptable under any circumstance."

Separately, police in PNG have confirmed another tribal dispute, leaving around 14 people dead.

As the country's leaders attempt to tackle the recent outbreak of violence, the latest massacre has taken place in the Mul-Baiyer district, around 300 kilometres away from the Tari-Pori district.

Thousands of people are displaced every year in PNG due to tribal violence, where the targeting of women and children is also becoming increasingly common in tribal conflicts.

The International Committee of the Red Cross (ICRC) in Papua New Guinea told the ABC that tribal violence is a "historical phenomenon" in the country which has been exacerbated by the use of guns.

They likened the humanitarian consequences of tribal disputes to war-torn countries such as Iraq, Syria and Afghanistan.