Australian Open bosses on Tuesday slapped a blanket ban on any display of Russian or Belarus flags at Melbourne Park.

The move came in quick response to a complaint by Ukraine’s ambassador when a Russian flag was spotted in the stands during a Monday opening day women’s match between a Ukrainian and a Russian.

“Flags from Russia and Belarus are banned onsite at the Australian Open,” Tennis Australia said in a statement.

“Our initial policy was that fans could bring them in but could not use them to cause disruption. Yesterday, we had an incident where a flag was placed courtside.

“The ban is effective immediately. We will continue to work with the players and our fans to ensure the best possible environment to enjoy the tennis.”