The family of a female Iranian asylum seeker, who was allegedly raped three months ago in Nauru, say the Federal Government has refused to allow her to be treated in Australia.

In May the 23-year-old woman left the Nauru detention centre to visit friends on the island.

She was raped as she made her way back to the family camp.

Her brother said following the attack, staff from medical provider, IHMS, informed the family his deeply traumatised sister would be sent to Australia for treatment.

"Some of them directly talked with us and said that in the next few days, you and your family, will transfer from here to Brisbane for having special medical care," he said.

But that has not happened.

Since the assault the woman has been kept in a separate compound away from her family.

"Because of her depression, two times she tried to kill herself," her brother said.

"One time with cutting her hand and the last with a bottle of insecticide.

"They're keeping her in IHMS hospital after last suicide [attempt] for more than three weeks. And after that time she hasn't talked with anybody, she hasn't eaten anything."

While local police initially denied the assault had occurred, they eventually conceded it had and began to investigate. However, no charges have been laid.

Australian Border Force has also confirmed it is aware of the incident and said it takes allegations of sexual assault seriously.

A spokesperson for the Immigration Minister said in a statement: "The individual concerned is receiving appropriate medical and mental health support and care in Nauru."

"Medical professionals have advised that the individual does not require a medical transfer."

Greens Senator Sarah Hanson-Young said the Government over-ruled a decision to bring the woman to Australia for treatment.

"The information that I've been given is that staff at the detention camp have said that she can no longer be transferred to Australia," Ms Hanson-Young said.

"That she won't be given the medical assistance she needs and that directive has come from Canberra.

"What we know is that nobody has been charged as a result of this. In fact witnesses haven't even had statements taken.

"These are the incidents that are going on on a regular basis inside Nauru and somebody needs to start taking responsibility for them."

Allegations of widespread sexual assaults on Nauru

A Senate Select Committee has been probing several allegations of corrupt behaviour and physical and sexual assaults within Nauru's detention centre.

Ms Hanson-Young said the report will be tabled within weeks.

"That process has shed a lot of light on a lot of incidents that the Government denied, and didn't want to talk about, were happening," she said.

"There is a cover up of the abuse and level of safety in the Nauru camp and the community as a whole."

However it appears unlikely the Iranian woman will receive medical treatment in Australia.

Last month a leaked IHMS document suggested asylum seekers in Nauru who required medical care would now be flown to Papua New Guinea.

The minister's office has confirmed asylum seekers may be transferred to other countries in order to receive medical treatment not available on Nauru.