Australian of the Year Pat McGorry is extending support for a Senate inquiry into Scientology, saying that its views on mental health are putting lives at risk.

The renowned mental health expert has joined psychiatry boss Louise Newman and the Brain and Mind Institute's Ian Hickie in urging senators to vote for an inquiry.

"They are the deniers of the realities of mental illness, which I find incredibly irresponsible and dangerous," News.com.au quoted him as telling ABC Radio.

The Senate is expected to vote on the issue, brought forward by independent Senator Nick Xenophon, by the end of next week.

McGorry met Xenophon yesterday to lend his voice to the cause.

"I'm concerned that any restriction or any discouragement of access to mental health care will cost lives and result in unnecessary disability for people," he said.

"The whole mental health field would support this call for an inquiry and it's something that's overdue in my opinion," he added.

Until now, only the Australian Greens have committed to voting for the inquiry and it needs more support if it is to get up.

Xenophon said Scientology had nothing to fear from a transparent inquiry where it would be given the right of reply.

He refused to abandon any victims of Scientology, saying that he could be a "completely stubborn bastard" when it came to pursuing important issues.

The church's Australian vice-president Cyrus Brooks has rejected the support of the mental health experts.

"That's the wrong way for them to go there. They're going into the field of religion and they're in the field of mental health," he said. (ANI)