The public should not be worried about the country's first convicted plane hijacker, despite her threats to reoffend, says the Mental Health Foundation.

Photo: David Hallett, The Press, Fairfax NZ / RNZ

Asha Abdille has almost completed her prison sentence and is threatening to hijack another aircraft if she gets the chance.

She stabbed both pilots on an Air New Zealand flight from Blenheim to Christchurch in February 2008. One passenger was injured in the incident.

The Somali refugee took knives onto the 19-seater plane, which was forced to make an emergency landing.

Abdille was sentenced to nine years in prison, and her sentence expires on 7 February.

She is currently held in a psychiatric unit in the Wellington region, but refused to attend her final Parole Board hearing in early December. A written summary of the hearing, obtained by RNZ, said Abdille was still classified as high risk and has "said that she will attempt to hijack another plane and has threatened to set herself on fire".

Mental Health Foundation chief executive Shaun Robinson said there was no cause for alarm.

"She is still under care, she is still under supervision, she is still under a compulsory treatment order. And given the record of the mental health system managing those types of situations extremely well, then no, I don't think people should worry about it."

However, mental health watchdog group Psychle said the secrecy around Abdille as she neared the end of her sentence was a recipe for disaster.

Psychle spokesperson Graeme Moyle said Abdille was clearly still dangerous.

"The Parole Board decision said there had been no reintegration plan made. [In] a previous decision I saw, she was uncompliant with medication, she was making threats of self-harm and threats to replicate her previous offending. So, based on that, I feel she's still a threat to the public."

Mr Moyle said her words should not be dismissed.

"Previous violence is, you know, a good indication of future violence, and if she's verbalising that to people - you'd have to go for the worst case scenario and take it seriously."

There should be transparency about her ongoing care, he said.

"It's not private medical information, it's public safety information. To use the Privacy Act is ridiculous, we're not asking what pills she's on, what her condition is. Just want to know where she is, [that] people are going to be safe, that she's going to be monitored."

But the Mental Health Foundation's Shaun Robinson said the system was transparent enough already.

"There is no reason for anybody's mental health treatment to need to be spotlighted in the public. There isn't an issue of transparency. There is an issue of a person's mental health, and of the community safety, but those can be managed without it having to be played out publicly."

The Ministry of Health would not specifically discuss the ongoing oversight of Abdille, saying it would only consider commenting on an individual if the circumstances were exceptional and agreement had come from the patient.

Mr Moyle said the public deserved more information.

"I'm very cynical about how [the ministry] handle offenders like this. Even if she is held securely in a forensic mental health facility, there's no guarantee that she will be detained in a secure environment. They're very lax and very free to give unescorted leave to patients in her situation to test them out in a community environment," he said.