Up to 30 per cent of patients in NSW public hospitals would be better off in more appropriate facilities such as aged care homes, the health minister says.

Hospitals are increasingly being filled with patients who could be treated by a GP, as well as patients waiting for a place in aged care and those needing disability services occupying beds needed for acute care.

"It is a huge problem right across NSW," Brad Hazzard told reporters on Wednesday.

"At any one time we are probably looking at between 500 and 1000 patients in our hospitals - so the equivalent of two very large hospitals occupied by people who are waiting to get into aged care or needing services for disabilities," he said.

On average every hospital in NSW has at least 10 per cent and up to 30 per cent of beds "occupied by residents who would probably prefer to be in an aged care facility where they could have their own things around them".

"And we would actually prefer obviously to have those clinical spaces available for patients," he said.

The NSW and federal governments were working closely to resolve the issues in the state's hospitals, he said.

"But it is a big task and it does impact on ... the availability of beds,' he said.

He was speaking at the opening of a new clinical services building at Campbelltown Hospital in Sydney's southwest, alongside Premier Dominic Perrottet who used the occasion to renew his push for national reform of the healthcare system.

"It's not about states going to the federal government asking for further funding," the premier said.

"It's about saying what is the best health system possible?"

"If we achieve just one thing this year as a country, and that is a better integrated health system between the federal government and state and territory governments, that will be a real success and will ensure that we have the best patient care across the country," he said.

The government also announced more than 3600 graduate nurses and midwives will begin their careers in 130 NSW public hospitals and health services this year - the largest-ever intake of any state or territory.