Police have arrested 159 people attending the Listen Out Festival in Sydney at the weekend for drug offences.

Of those arrested, 154 were charged with drug possession and five people were charged with supplying drugs.

The event was held on Saturday at Centennial Park in Randwick and attracted 34,000 festival-goers.

Twelve people were hospitalised for drug-related matters and seven for drug-related issues.

NSW Premier Gladys Berejiklian told the ABC she was waiting on recommendations to be made by an expert panel she recently put together, in relation to improving the safety of music festivals.

The expert panel was announced two weeks ago after two young people died from drug overdoses at the Defqon.1 music festival in Penrith.

"I want people to be able to enjoy music festivals — they are an important part of NSW's entertainment scene," Ms Berejiklian said.

"We need to do everything we can to protect the safety of concert-goers and people attending music festivals.

"I fully support and appreciate the hard work of our police and medical professionals at these events in keeping people safe."

Pill testing ruled out

However, Ms Berejiklian has previously ruled out pill testing at music festivals, even if the expert panel recommended it.

Harm reduction advocates have called for pill testing to take place at music festivals, and point to the success of a pill testing trial at the Groovin the Moo festival in Canberra earlier this year.

But Ms Berejiklian said there was "no such thing as a safe illicit drug".

Police also charged three people for resisting arrest at Listen Out, along with three for assaulting police, four for "failing to quit offences" and one for offensive behaviour.

Operation Commander, Superintendent Karen McCarthy, said the operations were conducted "because the wellbeing and safety of attendees is our number one priority".

Superintendent McCarthy said festival-goers were generally "well-behaved" and "enjoyed the event".

"However there appears to be a small section of the community that continues to possess and deal in illegal substances, despite our warnings," she said.

"Both uniformed and covert officers attend these festivals so if you choose to act illegally or anti-socially you will never know if the person standing next to you is a police officer."