SYDNEY - Asylum seekers torched nine buildings at an Australian detention center in a night of wild riots, with the government vowing on Thursday that it would not cave in to violence.

Demonstrations began late on Wednesday at the Villawood Detention Centre in western Sydney, with an estimated 100 detainees involved at the height of the drama.

Firefighters were at one stage pelted with roof tiles and pieces of furniture as they tried to douse the blazes, and riot police were called in to protect them.

A computer room, kitchen, medical facilities and a laundry were among the buildings destroyed.

The immigration department said the fires had been contained but some people remained on the roof, including an Iraqi, three Kurds and two Iranians, sitting beside a large white sign that read "We need help".

Immigration spokesman Sandi Logan condemned the "appalling" behavior of rioters.

"At one stage many of the protesters were hurling roof tiles and pieces of furniture, and other clumps of wood at the firefighters," he said, adding that "miraculously" no injuries had been reported.

One of the Iranians still on the roof told reporters by phone he was "very frustrated" after his visa application was turned down.

"I'm not an animal, I'm human. I've been in the detention center for 20 months," he said. "I don't have a criminal record. We're put in prison just for freedom."

Australia has a policy of mandatory detention for asylum seekers while their claims are processed, and generally holds them on remote Christmas Island, 2,600 kilometers from the mainland in the Indian Ocean.

But the increasing number of people arriving by boat - 6,500 last year, many from Afghanistan and Sri Lanka - has seen increasing use of mainland centers, including Villawood, which houses about 400 people.

Protests erupted at the Sydney center last September after a Fijian leapt to his death from a roof in front of horrified onlookers, shortly before he was due to be deported. It sparked a tense 29-hour standoff with other detainees.

The Christmas Island facility endured days of riots last month, with about 250 inmates setting fire to accommodation tents and hurling makeshift explosives at police, prompting them to respond with tear gas.

Brami Jegan, from the Refugee Action Coalition, told ABC radio she believed the Villawood disturbances were prompted by stress and frustration.

Agence France-Presse