The Serbian star had just booked his place in the tournament semifinal with a straight sets thumping of Russian opponent Andrey Rublev in Rod Laver Arena on Wednesday night.

After the match a group of fans unfurled Russian flags near the stadium, including one featuring Vladimir Putin’s face, chanting pro-Russian slogans.

Tennis Australia said four people “revealed inappropriate flags and symbols and threatened security guards”. Police were called and they were ejected from Melbourne Park.

A video later posted to a pro-Russian Australian YouTube account showed Djokovic’s father Srdjan posing with a man holding the Putin flag.

It was captioned: “Novak Djokovic’s father makes bold political statement.”

Serbian tennis reporters confirmed it was Djokovic’s father and the Melbourne Age newspaper reported he said in Serbian: “Long live Russia.”

Spectators are banned from having Russian or Belarusian flags at the Grand Slam after Ukraine’s ambassador to Australia and New Zealand, Vasyl Myroshnychenko, demanded action when they were seen among the crowd last week.

He said on Twitter today that the latest incident was shameful.

“It’s a full package. Among the Serbian flags, there is: a Russian flag, Putin, Z-symbol, so-called Donetsk People’s Republic flag,” he tweeted with a link to the video.

“It’s such a disgrace … @TennisAustralia @AustralianOpen.”

Another man was photographed by AFP inside the stadium during Djokovic’s match with a pro-war “Z” symbol T-shirt – associated with support for Russia’s invasion of Ukraine.

Since Russia’s invasion of Ukraine, Russian and Belarusian players have normally competed under a neutral white flag as independents, as is the case at the Australian Open.