SYDNEY (AP) — Australian police used pepper spray to quell a Thursday night protest at an offshore detention center that has been the scene of unrest in the past, officials said Friday.

Protests frequently erupt at the overcrowded Christmas Island center, where Australia processes asylum seekers who have often fled poverty and war in the Middle East or Asia. In March, more than 200 detainees demanding visas set fire to buildings and tried to escape from the center. Police also responded to that demonstration.
As many as 100 detainees began protesting late Thursday night, according to the Australian Federal Police, who were called in by the security firm that runs the center. Some detainees fashioned weapons from metal poles and concrete and began throwing objects at officers, police said in a statement.
Police responded by firing beanbags and used pepper spray, the statement said.
One worker for the firm that runs the center suffered minor injuries, the Immigration Department said. No detainees were injured, according to an Immigration spokeswoman, who spoke on condition of anonymity, citing policy.
The department said the center was calm Friday, though Immigration Minister Chris Bowen later told Sky News that three men continued their protest from atop a building at the center. One eventually climbed down, but two remained on the roof Friday afternoon, he said.
Authorities are investigating the unrest, and Immigration officials said anyone convicted in connection with the protest could be denied a visa on character grounds.
“Protests and getting on roofs does not change visa outcomes, and clearly inappropriate and potentially criminal behavior can impact on visa outcomes in a very negative way,” Bowen said.
Most asylum seekers arriving by boat to Australia are held at Christmas Island — an Australian territory in the Indian Ocean that is closer to Indonesia than to the Australian mainland — and the center is often overcrowded. The UN Refugee Agency urged Australia on Friday to seek alternatives to detention and said its new report shows that automatic detention violates international law and does not appear to deter asylum seekers.
Successive Australian governments have struggled to find a way to process refugee claims that satisfies international requirements but isn't so lenient that it makes the country an attractive target for people-smugglers.
The current government has proposed a swap with Malaysia: Australia would send 800 asylum seekers to its Asian neighbor in exchange for 4,000 certified refugees.
Prime Minister Julia Gillard says the plan would serve as a deterrent to asylum seekers considering making the dangerous sea journey to Australia because it would make the country less of a sure bet for resettlement. Critics, however, note that Malaysia has not signed the Refugee Convention or Convention Against Torture.