Officers were called to Antique Bar in Elsternwick following reports of a man assaulting patrons at the premises about 2.15am, police said in a statement.

The man has been identified by friends and former colleagues as Spiro Boursine (also known as Spiro Boursinos), founder of Australia's pioneering outdoor dance festival.

Close friend and former Earthcore general manager Gary 'Binaural' Neal told The Age that he had confirmed the sad news with Mr Boursine's family members on Saturday.

"Spiro created a subculture in Australia that turned in to one of the biggest alternative community followings that I think Australia's got within the dance scene," Mr Neal said.

"I mean, it created dance, it created fashion ... it became a lifestyle for many, many people.

"Without Spiro, we wouldn't have that.

"He's given me some of the most valued times in my life, to be honest, as a young person going to his events and then again working for him – it was my dream working in events and something I was proud of."

Earthcore was held in Elmore in 2017 after the festival was refused a permit for its former Pyalong site.

Frequent noise complaints were lodged with Campaspe Shire Council and the event went ahead without an approval for late-night noise.

Read more: Earthcore festival 2017 starts at Elmore Events Centre

Several high-profile acts pulled out at the last minute after they did not receive payment. There was also a delay in the payment to the Elmore Events Centre and contractors.

Elmore Events Centre president Derek Shotton said they ultimately received their payment in full from Mr Boursine.

Mr Shotton acknowledged that Mr Boursine was a shrewd businessman and their experience with Earthcore had been good advertising for the events centre.

“It got our name out there a bit with people in the industry,” he said.

Despite Mr Boursine’s desire to hold the event in Elmore again in 2018, a different venue was chosen.

George Grigoriadis, who worked with Mr Boursine for six years, said Australia had lost an innovator.

"He was an innovator of the festival scene in Australia and it's a sad day," Mr Grigoriadis said.

Dark Riddims managing director Jimmy Barber posted on Facebook: "Today the Australian electronic music scene lost a polarising icon. Love him or hate him, he was still an icon and RIP Spiro."

It is understood Mr Boursine had experienced heart issues in the past.

Police would not confirm the name of the man who died, only that he was 45 years old and from Cheltenham.

Victoria Police spokeswoman, Leading Senior Constable Melissa Seach, said in a statement that when police arrived at the bar, the man was being held down by a number of people.

"Police arrested the man and placed him in handcuffs when he lost consciousness," she said.

"Police attempted to revive the man until Ambulance Victoria arrived and took over.

"Despite the efforts of emergency service personnel, the man died at the scene.

"A post mortem examination will be conducted to try and determine the cause of death."

The homicide squad, overseen by Professional Standards Command, will investigate his death.

Antique Bar owner Sam Falleti declined to comment.

 – The Age