A Sri Lankan refugee who killed himself in Sydney's Villawood detention centre was not considered suitable for community placement by security agencies, Australia's Immigration Minister Chris Bowen says.
The Tamil man, who had been detained at the western Sydney centre since late March 2010, was deemed to be a refugee in August.
He was one of 462 people awaiting security clearance from the Australian Security Intelligence Organisation (ASIO).
"There are cases, and this is one, which are more complex and which ASIO will need to take more time to consider whether this person would be a risk to national security," Bowen said.
"There was consultation with the relevant security agencies, that's ASIO, and the advice was it was not appropriate in this case."
Department of Immigration officials were trying to contact the dead man's brother in Sri Lanka, but so far had not had success, he said.
Bowen confirmed the man had sought leave to attend a Hindu festival, which was to be held at Villawood yesterday, but the request had been knocked back.
Three people died at the Villawood centre in 2010, and the dead man had been a resident at the time of some of those deaths.
Bowen said the Department of Immigration was prepared for more riots at Villawood in light of the latest death.
"Certainly, experience does show us that when you have an incident like this, a tragic incident, it does and can lead to increased tension," he said.
"Obviously we're taking whatever steps we can to ensure that the situation is handled appropriately.
The man who killed himself had been housed in residential housing adjacent to the main Villawood detention centre which accommodates families and vulnerable people.
Bowen denied the immigration system was in crisis, but he said detention facilities were under pressure.