A western Sydney hospital's ad offering filming space in empty hospital wards was a "mistake", the NSW premier says despite support for the initiative from his health minister.

Campbelltown Hospital had posted a tender for "vacant/unused wards that can be used for filming for TV/Ads/Movies and other similar such mediums".

"It clearly shouldn't have happened and it's wrong," Premier Dominic Perrottet told reporters on Friday.

"My advice is that the decision was made by a health procurement official.

"Once the health minister realised, he fixed it.

"Mistakes get made. It wasn't made by a senior person."

But the premier appears out of step with his health minister, who said the official should be congratulated for formalising an ad-hoc process that was already happening.

Hospitals had regularly received filming requests from TV stations and film crews before the practice was halted due to the pandemic, he said.

Campbelltown Hospital recently expanded at a cost of $750 million and had a new acute service, leaving yet-to-be-refurbished wards in the older part of the hospital unable to be used for patients.

"A senior procurement officer simply put out what would normally happen anyway," Mr Hazzard told reporters on Friday.

"He asked for expressions of interest, rather than having individual networks coming in regularly asking for space. It's a logical thing to do, I'm not going to bag a senior health officer."

Mr Hazzard lashed Labor for criticising the official who was "beyond mortified for the words used".

"Labor should lay off on picking on staff members who are actually trying to do their bit for extra money (for the hospital), but also in an organised way," he said.

Labor had claimed the government was "more interested in creating fictional treatments than actually treating patients in need".

"This is outrageous," Opposition leader Chris Minns said on Friday.

"This isn't Grey's Anatomy, it's a real hospital with sick people."

Labor pointed to recent health data stating 42.2 per cent of critical emergency treatment started within the recommended 10-minute time window at Campbelltown Hospital in the June quarter.

Ten per cent of patients waited more than 75 minutes to be transferred from an ambulance to a bed in the hospital.

Mr Hazzard denied the government was neglecting the health system in southwestern Sydney.

"We have more staff in our health system and more hospitals than have ever been built in NSW," he said.

Mr Hazzard, who has been the state's health minister for the last five years, will retire from politics after the state election in March.