Updated

Police in Papua New Guinea opened fire after hundreds of men pushed down the perimeter fence and broke out of an Australian-run detention camp for asylum seekers during a violent protest in which one inmate was killed and scores were injured, an Australian official said.

Papua New Guinea is one of two South Pacific nations where Australia operates camps to house thousands of asylum seekers, mostly from war-torn countries in the Middle East, who have tried to enter the country illegally after dangerous sea journeys from Indonesia. Australia intercepts them at sea and sends them to camps at Manus Island or the tiny Pacific atoll nation of Nauru while their refugee claims are evaluated for resettlement in those countries.

The unrest at the camp in Papua New Guinea, which began late Monday and ended Tuesday, has heightened pressure on Canberra to close these camps but the government was holding firm, saying it is an effective deterrent against asylum seekers.

The provocation for the violence at Manus Island was not immediately clear. Australian Immigration Minister Scott Morrison described the violence as the latest in a series of protests at the camp, which houses around 1,300 men from countries including Afghanistan, Sudan's Darfur region, Iraq, Iran, Lebanon, Pakistan, Somalia, and Syria.

"This is a tragedy, but this was a very dangerous situation where people decided to protest in a very violent way and to take themselves outside the center and place themselves at great risk," he told reporters.

He said one man died from head injuries as he was taken to the hospital. He would not disclose the victim's nationality, or say how he had sustained the injuries. Another person was shot in a buttock and was flown to the Papua New Guinea capital Port Moresby while one man was flown to Australia for treatment of a fractured skull, he said.

In all, 77 people received medical treatment including 13 who were seriously injured, he said.

Morrison initially said the injuries had occurred outside the camp but later said he was uncertain whether the fatal injuries had been inflicted within the camp or outside. Papua New Guinea authorities would investigate, he said.

He said Papua New Guinea police opened fire after detainees pushed down the perimeter fence and spilled into the street around the camp, whose security guards had unsuccessfully used shields to push back the asylum seekers.

There were conflicting reports about the violence.

Ian Rintoul, spokesman for the Australian advocacy group Refugee Action Coalition, said he had spoken to inmates inside the Manus camp and was told asylum seekers had been attacked by police and local residents.

Gangs of police and locals — armed with machetes, pipes, sticks and stones — had roamed from compound to compound within the camp attacking asylum seekers, the coalition said.

"It must be clear now that asylum seekers cannot live safely on Manus Island," Rintoul said in a statement.

But Morrison and the contractor that operates the camp, G4S, denied that any outsider had breached the perimeter fence or attacked anyone inside the camp.

Local Manus lawmaker Ron Knight blamed G4S for "shoddy camp management."

The violence followed a less serious brawl at the same facility on Sunday night that led to the arrests of eight asylum seekers and another 19 being treated for injuries.

Amnesty International condemned the camp and joined Australian opposition parties in calling for an independent investigation of the violence.

G4S said Tuesday that camp staffers were trying to account for all the detainees after the breakout.