UPDATE 1-One dead, many hurt as asylum seekers riot at PNG detention camp

* One asylum seeker killed, another critically injured

* Critics call for closure of detention centre

* Centre on small PNG island used for asylum seekers trying to reach Australia

(Recasts with death, number of injuries, quotes from immigration minister)

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.

One person was in critical condition with a head injury and another sustained gunshot wounds during clashes that erupted after asylum seekers forced their way out of the centre on a 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.

"Our sympathies are extended to the transferees - that person's family and friends who would have been in the facility as well," Immigration Minister Scott 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.

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.

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.

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 detention centre in the remote Australian territory of Christmas Island sewed their lips together as part of a hunger strike in protest over their treatment.

Morrison said the latest riot began when detainees forced their way through fences surrounding the centre and clashed with Papua New Guinea police, although it remains unclear whether others were involved in the violence.

The 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.

Security guards have regained control of the centre, which had not been damaged, and PNG police had caught most of the detainees who had escaped during the latest incident, Morrison said. He said it was possible some were still missing.

The unrest in Papua New Guinea quickly drew calls from critics to shut the facility. The U.N. High Commissioner for Refugees said in a November report the centre failed to provide "safe and humane conditions of treatment in detention".

Sarah Hanson-Young, a Greens Party senator and vocal critic of the government's asylum seeker policies, said responsibility lay with Abbott and Morrison.

"The government was warned about the toxic environment on Manus Island repeatedly by organisations like Amnesty International and the UN but those warnings were ignored and dismissed," she said in a statement.

(Editing by Paul Tait)

((matthew.siegel@thomsonreuters.com)(+61 2 93731811)(Reuters Messaging: matthew.siegel.thomsonreuters.com@reuters.net))

Keywords: AUSTRALIA IMMIGRATION/MANUS