Putting advertising logos on the Sydney Opera House could breach Australia's environment and heritage laws, one think tank says.
The Australia Institute wants an urgent review of whether the decision to promote a horse race on the iconic building's sails conflicts with its heritage listing.
"We have heritage laws for a reason," institute executive director Ben Oquist told reporters on Tuesday.
"Whatever you think of the light show, it should comply with Commonwealth environment law."
Mr Oquist says the federal Environment Department should look at the plan to promote The Everest horse race on the opera house to see if it breached the law.
"There are mixed views about whether it should go ahead, but it is significantly controversial now and in that case, in that situation it's even more important that the law is upheld," he said.
He called on Environment Minister Melissa Price and her department to step in.
Mr Oquist said it was possible other light shows on the opera house had also breached environmental laws.
He said when former Liberal environment minister Ian Campbell put the Sydney Opera House on the heritage list, the floodlit sails at night were a key part of the listing.
Prime Minister Scott Morrison this week described the building as the "biggest billboard" in Sydney.
The barrier draw for The Everest is due to be projected on the sails of the Opera House from 8pm AEDT on Tuesday, alongside a planned protest on the foreshore.
