The protest by 11 asylum seekers at a Sydney detention centre, sparked by the suicide of a fellow detainee, will not prevent their deportation, the federal government says.

Nine Tamils, one Iraqi and one Afghan began their rooftop protest at the Villawood detention centre in the city's west on Monday afternoon and were still refusing to come down this morning.

A 36-year-old Fijian man facing deportation committed suicide on Monday morning at the centre.

All the men on the rooftop have exhausted the application process for asylum status and face being returned to their homeland.

Immigration Minister Chris Bowen said their actions would do nothing to prevent their deportation.

"I understand that people who are very keen to stay in Australia will in desperate circumstances think of other ways to make their case," Mr Bowen told Fairfax radio on Tuesday.

"Our immigration officials determine who gets asylum after a very rigorous process.

"And it's not determined by a protest, and a protest won't change an immigration outcome."

Immigration department spokesman Sandi Logan said negotiators had been on the scene of the standoff overnight and into Tuesday morning.

The negotiators included local Tamils, he said.

Mr Logan said the men were protesting against the handling of their visa applications, and their actions would neither help nor hinder them.

"We continue to be hopeful that reason will prevail, that logic will prevail, and that they will understand that remaining on the roof is not going to change an outcome. It's not going to secure a different outcome to that which they currently have," Mr Logan told ABC television.

Mr Logan said he had not heard about claims the Villawood centre was understaffed, and he believed its manager, Serco, was managing well in a sometimes challenging environment.

Refugee advocate Sara Nathan has been in mobile phone contact with some of the rooftop protesters, who say the rejections of their applications contained factual errors and they were not given legal help during the process.

Ms Nathan told AAP: "They're saying, `Can we have a review of our case because you made a mistake. This is our lives. If you return us, we will be tortured and/or killed'.'

Refugee Action Coalition spokesman Ian Rintoul says the men want assurance their cases will be reviewed again before they will come off the roof.

"They want an independent and transparent review of their cases and they want to meet with the immigration officers," he told AAP.

"They've made it clear that they can't go back to Sri Lanka."

Mr Bowen said just under 5000 people were being held in detention centres on Christmas Island and the Australian mainland.

- AAP