The NSW government is standing by its decision to force Sydney Opera House management to promote a horse race, despite an increasingly vocal community backlash to the plan.

Premier Gladys Berejiklian intervened late last week after shock jock Alan Jones publicly berated Opera House chief executive Louise Herron, who had ruled words or branding promoting The Everest race could not be projected onto the building’s famous sails because “it’s not a billboard”.

By Monday afternoon, thousands of people had signalled their intention to join a “light-based” protest at the Opera House on Tuesday night, when the sails will be used as a backdrop to promote the barrier draw for Saturday’s $13 million race.

“Bring things that create light in order to disrupt the use of the sails for advertising purposes – they are reserved for art,” the organisers said of their planned “passive protest”.

They warned protesters not to bring drones, laser pointers or some torches, which might be illegal.

“The original idea of this action was about collective, critical mass. If enough people shine their phones at the Opera House, set them to strobe or even shine them back at the TV cameras, then it’s inoffensive but ultimately disruptive.”

A change.org petition supporting Ms Herron had attracted nearly 170,000 signatures by Monday afternoon (ADST).

Former Opera House chief executive Michael Lynch added his voice to the opposition, saying promoting a horse race on the building was “crass, inappropriate and offensive”.

Past victories by Australia’s rugby and cricket teams had been celebrated using the Opera House, but they were very different scenarios, he said.

“I don’t think the general public feels any similar feelings towards a horse race where you have to pay $600,000 to enter,” Mr Lynch told ABC radio on Monday.

National Trust NSW conservation director Graham Quint labelled the move “crass commercialism”.

“The World Heritage listing requires not only that the building be preserved in its fabric but also that it be presented properly,” he told ABC TV. “In no way under the current conservation management plan should this be allowed.”

But Ms Berejiklian on Monday insisted she was “incredibly comfortable” with her intervention.

“We would never do anything that wouldn’t support the iconic stature of the Opera House but it is also extremely important for us to promote those events that bring jobs and economic activity to NSW,” she said.

At the weekend, Prime Minister Scott Morrison said the Opera House was “”the biggest billboard Sydney has” and it should be utilised, along with the Harbour Bridge.

On Monday, he took to radio station 2GB, in the company of host Alan Jones, to defend his view.

“It’s not like they’re painting it (the promotion) on there,” he said.

Jones used his radio show to deny bullying Ms Herron last week, arguing she had been spouting “nonsense” about heritage when he wanted an answer.

Racing NSW chief executive Peter V’landys on Monday told Sky News he and his staff had received death threats. A spokeswoman for NSW Police said later she was unaware of any reports of such threats.

Mr V’landys said Racing NSW had been negotiating with the state government for more than a year, and initially wanted to use the Harbour Bridge to promote the race.

“The Opera House was the alternate venue put forward by the NSW government, which wanted to support the promotion of the event internationally,” he wrote in an opinion piece published by Fairfax.

“We are promoting a unique Sydney event, The Everest, not gambling.”

Mr V’landys also said a “vast majority” of the negotiations happened before Jones got involved last week.

“Call me naive but I certainly didn’t expect there would be such a reaction to us using the Opera House sails for 10 minutes to promote The Everest event internationally.”

-with AAP