On Friday, Ukraine's ambassador to Australia called on tennis authorities to prohibit Novak Djokovic's father from attending the Australian Open, after footage surfaced of him being photographed with fans brandishing Russian flags.

"He should be stripped of his accreditation," Ambassador Vasyl Myroshnychenko told AFP.

Myroshnychenko also called on Djokovic, who faces Tommy Paul in the semifinals of the tournament, to personally apologise and to clarify his stance on the Russian invasion of Ukraine. "He should apologise for what has happened, and condemn the Russian invasion of Ukraine," he demanded.

A video posted to a pro-Russian Australian YouTube account on Thursday showed Djokovic's father Srdjan posing with a man holding a Russian flag with Vladimir Putin's face on it. The video 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 that he said in Serbian, "Long live Russia."

Another man was photographed by AFP inside the stadium during Djokovic's match with a T-shirt bearing the Russian pro-war "Z" symbol.

Ukrainian Marta Kostyuk, who lost in the women's doubles semifinal, said the behavior was hurtful, but was reluctant to comment on whether Djokovic's father should be banned. "No matter what I say, I will be hated until the rest of my life, especially by very aggressive Novak fans," she told reporters.

Last year, Djokovic was deported from Australia for refusing to be vaccinated against COVID-19 – the controversy overshadowing the start of the tournament.

Myroshnychenko said the player's response to the latest controversy would again draw attention away from what was happening on the court. "The last Open was all about Djokovic. Now it's all about Russian flags and Djokovic as well," he said.

Ukrainian former player Alex Dolgopolov on Twitter said open support for what he called a "genocidal regime" was "absolutely disgusting".

Myroshnychenko was instrumental in persuading Australian Open organisers to ban Russian and Belarusian flags from this year's Grand Slam.

Honor and dignity

Russia's embassy in Australia had hit back at the ban, calling it "another example of unacceptable politicisation of sports."

Simeon Boikov, who runs the YouTube channel that posted the flag footage, urged Russian supporters to descend on Melbourne Park ahead of Djokovic's quarterfinal match against Andrey Rublev. "This is about honor and dignity now. This is an attack on honour and dignity. This has got nothing to do with the war," he said in a video message.

Australian Prime Minister Anthony Albanese said he did not "want to see any support given to the Russian invasion of Ukraine."

The country's conservative opposition leader, Peter Dutton, called the behavior of Djokovic's father "bizarre."

"The Russian onslaught continues and, frankly, everybody of goodwill should be trying to deter, not encourage President Putin," he told Australia's Nine Network.

Tournament organiser Tennis Australia said on Thursday it would continue to work with security to enforce entry rules, without directly addressing the incident with Djokovic's father.

"Players and their teams have been briefed and reminded of the event policy regarding flags and symbols and to avoid any situation that has the potential to disrupt. We continue to work closely with event security and law enforcement agencies," it said.

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