As an inquiry into alleged multi-million-dollar corruption in WA's Housing Authority gets underway, the state's Public Sector Commissioner said she was "incredulous" to find out it could have been going on for several years.

Key points: Paul Whyte allegedly used false invoices to steal millions of dollars in public money

Paul Whyte allegedly used false invoices to steal millions of dollars in public money A review of the Housing Authority where he used to work has also been ordered

A review of the Housing Authority where he used to work has also been ordered Mr Whyte remains in a critical condition in hospital after an incident at his home

The Premier asked Commissioner Sharyn O'Neill to carry out the inquiry after high-ranking Department of Communities executive Paul Whyte was charged with corruption last week.

The Corruption and Crime Commission (CCC) initiated the investigation and said the charges followed an intensive joint probe with WA Police.

It was alleged under the two charges that Mr Whyte, who has been suspended from his assistant director general role in the department, stole $2.5 million.

But police subsequently revealed in court they were investigating whether up to $25 million was taken over more than 10 years.

Mr Whyte remains in a critical condition in hospital after an incident at his Mosman Park home late on Sunday afternoon.

Mr Whyte was taken to hospital on Sunday after what police called an "incident" at his home. ( ABC News: Keane Bourke )

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Multiple investigations underway

Ms O'Neill told ABC Radio Perth she was surprised to learn of the charges because she knew about the checks, balances and controls that were already in place.

She had been called on by the Government to conduct the review at the same time the criminal investigation was taking place.

"It is a little different to some other reviews because this is a live investigation and the preference, or the first order, is around the criminal investigation that the police and the CCC are undertaking," she said.

"We will respect that and in no way cut across that.

"So I'll take some direction from those bodies about who and when it's appropriate for us to talk to individuals."

Jacob Anthonisz was granted bail after appearing in court last Friday. ( Supplied: Kisses in Chaos )

Mr Whyte and a second man, 43-year-old Jacob Daniel Anthonisz, are accused of creating false invoices and then transferring the money into company bank accounts before withdrawing it for personal use.

Mr Anthonisz is not employed in the public sector.

Mr Whyte, who has been suspended from his position at the Department of Communities, and Mr Anthonisz were both granted bail after appearing in court on Friday.

Unaware of any Housing Authority concerns

A spokeswoman for Ms O'Neill said she first heard of the allegations against Mr Whyte last Wednesday night, the day before they were revealed publicly by police.

Mr Whyte has been suspended from his post at the Department of Communities. ( ABC News )

Ms O'Neill said she was not aware of any similar alleged activities in her previous role as director general of the Department of Education.

"If there were issues that were raised within education we dealt with them swiftly and I had a very strong approach to integrity," she said.

"I haven't heard in this role, or previous roles, concerns raised about the Housing Authority."

Ms O'Neill said her inquiry could be considered independent because she was a statutory officer, not a public servant, and was independent of the Government.

She said she believed her inquiry's report would be made public.

'There have to be standards set'

Ms O'Neill was also hoping to introduce a "whole-of-sector" strategy in dealing with integrity issues across the WA public service.

"I was surprised to see there isn't a whole-of-public-sector strategy to deal with or raise issues around integrity," she said.

"So I have one out for consultation right now that lays out an approach for all government departments to participate in.

"There have to be standards set. That's what I would like to do with agencies, say, 'here are the kinds of things you need to have in place, detection systems, culture, accountability, policies, procedures'.

"The director generals are very supportive."

Sharyn O'Neill has plans for a "whole of sector" strategy for dealing with integrity issues. ( ABC News: Rebecca Carmody )

Opposition Leader Liza Harvey has called for an audit of the entire public sector payment system in the wake of the allegations involving Mr Whyte.

She said an investigation into the Department of Communities and the Housing Authority was not enough.

"A sector-wide audit to look at the processes around purchase orders, invoices, payments, those sorts of things, I think is required," Ms Harvey said.

"I don't think we need a royal commission, we had a royal commission that then established the CCC, clearly the CCC has done its job here.

"[But] potentially additional funding for the CCC to have further investigations may be warranted."

