* One asylum seeker killed, another critically injured
* Critics call for closure of detention centre
* Rights groups say violence started by villagers, police
* G4S security group says order restored
By Matt Siegel
SYDNEY, Feb 18 (Reuters) - An asylum seeker was killed and at least 77 injured in the second riot this week at a detention centre in Papua New Guinea used to process asylum seekers, Australia's immigration minister said on Tuesday.
Minister Scott Morrison said the riot began when detainees forced their way out of the centre, but refugee advocates said it was triggered when Manus Island residents and police stormed the facility, attacking the asylum seekers.
One person was in a critical condition with a head injury and another sustained gunshot wounds during the clashes on the small island in impoverished Papua New Guinea.
The facility is part of Australian Prime Minister Tony Abbott's tough stance against asylum seekers but it has come under fire over human rights concerns.
Australia uses detention centres at Manus Island and another on the tiny Pacific island of Nauru to process would-be refugees sent there after trying to get to Australia, often in unsafe boats after paying people smugglers in Indonesia.
"Our sympathies are extended to the transferees - that person's family and friends who would have been in the facility as well," Morrison said in reference to the dead asylum seeker.
"If people choose to remove themselves from that centre then they're obviously putting themselves at much greater risk and in an environment where there is violent behaviour," he told reporters in the northern Australian city of Darwin.
The latest incident followed an attempted breakout from the Manus Island facility on Sunday night, when 35 asylum seekers briefly escaped. Nineteen were injured and eight arrested in that incident.
Refugee advocates said detainees and staff had told them the violence started again when police and Manus Island villagers stormed the facility after dark and began attacking detainees.
"Locals armed with machetes, pipes, sticks and stones - have bashed and cut asylum seekers. One asylum seeker has been thrown from the second floor of a building; others have suffered machete cuts," the Refugee Action Committee said in a statement.
CALLS FOR CLOSURE
The Sydney Morning Herald said it had spoken to a man whose brother was in the facility. Ghulam Murtaza told the paper he had received a phone call from his brother late on Monday saying villagers had come inside the compound threatening to kill them.
Britain's G4S, the world's biggest security group, which is responsible for security at the facility, said: "A number of transferees were injured after they breached the perimeter fence and the matter became a law enforcement issue for PNG authorities."
"Claims that the transferees breached the fence following internal attacks on them by local residents are unfounded," it said.
The firm, which employs over 620,000 people in some 120 countries, added that its staff were able to restore order within the centre without the use of force.
G4S has had a chequered time of late. In 2012 it failed to provide enough staff for the London Olympics, and has since been involved in problems with an electronic tagging contract in Britain and unrest at prisons it has run in South Africa and Britain.
Canberra's tough stance on asylum seekers, including offshore processing and a blanket ban on people arriving by boat ever settling in Australia, has been criticised by the United Nations and other groups as illegal and inhumane.
Refugee advocates say that long-term detention, combined with a lack of clarity on where and when the asylum seekers may be resettled, contribute to a host of mental health problems at the facilities.
Last month, detainees at a centre in the remote Australian territory of Christmas Island sewed their lips together as part of a hunger strike in protest over their treatment.
The unrest in Papua New Guinea quickly drew calls from critics to shut the facility. The U.N. High Commissioner for Refugees had already said in a November report it failed to provide "safe and humane conditions of treatment in detention".