A DARWIN doctor has told a parliamentary inquiry that a nine-year-old child in immigration detention tried to commit suicide.

Doctor Peter Morris, from the Northern Territory branch of the AMA, told the inquiry he was aware of the case, which occurred in May.

Dr Morris, who works at the Royal Darwin Hospital, later told the NT News that it was not an isolated incident.

He said other children from the centre had been treated, some for self-harm.

Dr Morris said there were about two adults turning up at the emergency department of the Royal Darwin Hospital for treatment each day.

A hospital spokeswoman referred the matter to the Department of Immigration and Citizenship.

A DIAC spokeswoman said she could not comment on the claims while the parliamentary inquiry was underway.

Meanwhile, an asylum seeker support group says mandatory detention is putting stress on relationships of those incarcerated, leading to domestic violence.

Adrianne Walters from the Darwin Asylum Seeker Support Advocacy Network told the parliamentary inquiry into Australia's detention network that detainees relationships were coming under stress.

"Mandatory detention is a contributing factor," Ms Walters said. "Relationships are breaking down and unfortunately sometimes it leads to domestic violence."

She said that SERCO staff have relied on reporting the incidents to police but failed to address the cause.

"The lesson in this perhaps is that not enough is being done to prevent it in the first place," she said. She also feared detainees could be brought before courts without legal advice.

For local updates on this and other stories, visit the NT News.