SUNDAY'S Western Derby will go ahead at Optus Stadium without a crowd after a decision from the Western Australia Government that was based on health advice. 

Premier Mark McGowan made the announcement at 10.30am AWST, just hours ahead of the clash between West Coast and Fremantle. 

The decision will be a significant financial blow to the Eagles, who had already estimated a cost of around $500,000 due to the previous COVID-19 restrictions. 

FULL STATEMENT West Coast v Fremantle closed to the public

A crowd of 45,000 had been expected under the restricted 75 per cent capacity announced on Thursday before the latest positive COVID-19 cases were discovered. 

"Having 45,000 people in the one location and all of a crush of getting into the stadium, we judged was too high a risk," McGowan said. 

"It's a tough decision. I know a lot of people love the Derby, it's a great spectacle. 

"But in light of what we've learnt overnight about the people that we don't know whether they're infected or otherwise, we just thought it was too big a risk today. 

INDICATIVE DRAFT ORDER Check out your club's picks

"It's better to miss out on a football game, as important as that is, than have cases in the stadium, or cases in the crush getting into the stadium and potential spread of the virus." 

McGowan said the decision had been made on health advice and communicated as quickly as possible. 

The Eagles and ticketing agencies will communicate with members and fans who have purchased tickets.