A group of armed soldiers broke down the gates to a hospital in the Papua New Guinea capital Port Moresby and began indiscriminately attacking people, leaving a medical student seriously injured, according to police.

The incident at the Port Moresby General Hospital on Sunday was condemned by police Commissioner Simon Kauba who blasted the soldiers for attacking "the very people they have sworn to protect and defend".

"This is totally uncalled for and unacceptable behaviour by members of a disciplined organisation," he said in a statement.

"I condemn this action in the strongest possible terms and will ensure that it is thoroughly investigated and those responsible will face the full force of the law."

The assault occurred just hours before Australian Prime Minister Kevin Rudd arrived in Port Moresby for talks with his counterpart Peter O'Neil, which are expected to focus on the Pacific nation's chronic law and order problems, among other issues.

Kauba said the soldiers arrived at the hospital in a truck armed with guns, machetes and iron bars and smashed down the gates before beginning their attack. At least six shots were fired.

Reports said it was payback for an alleged assault by medical students on two soldiers during a dispute over the use of an ATM at the hospital on Friday night.

Police brought the matter under control, Kauba said, but the attack left a dental student seriously injured and considerable damage to hospital property.

Crime and lawlessness in poverty-stricken Papua New Guinea is a serious concern throughout the country, including the capital where last month four Chinese nationals were hacked to death, with one reportedly beheaded and the others dismembered.

Papua New Guinea recently passed harsh new laws reviving the death penalty as it grapples with a wave of violent crime, particularly against women, which has drawn international condemnation.