Novak Djokovic's father seen posing with Putin supporters carrying Russian flags at Australian Open

Australian Open organizers have issued a reminder to players and their entourages about their policy on "inappropriate flags" after a video emerged showing Novak Djokovic's father posing for pictures with fans holding Russian flags.

Four people were kicked out of the Australian Open after displaying Russian flags — which have been banned from Melbourne Park — and threatening security guards, police and Tennis Australia said Thursday.

A Victoria Police spokeswoman said the four have not been charged but were evicted from the site.

The flags, at least one of which included an image of Vladimir Putin, were being waved during a gathering outside of Rod Laver Arena after Novak Djokovic beat Russian player Andrey Rublev in straight sets in the quarterfinals of the year's first Grand Slam tennis tournament Wednesday night.

A video posted on social media showed one supporter on the steps of Rod Laver Arena holding up a Russian flag with the image of Putin on it.

Late on Wednesday another video showed Djokovic's father Srdjan posing for pictures with fans holding Russian flags.

This is…quite a mess for the <a href="https://twitter.com/hashtag/AusOpen?src=hash&amp;ref_src=twsrc%5Etfw">#AusOpen</a>, to say the least.<br><br>Srdjan Djokovic posing with the pro-Putin rally last night just outside Rod Laver Arena.<br><br>The levels of security breakdowns that allowed for this are staggering.<br><br>Story/video via <a href="https://twitter.com/jamesgraysport?ref_src=twsrc%5Etfw">@jamesgraysport</a>:<a href="https://t.co/L4gtaKKNP6">https://t.co/L4gtaKKNP6</a> <a href="https://t.co/qnOx3MGYqB">pic.twitter.com/qnOx3MGYqB</a>

"Players and their teams have been briefed and reminded of the event policy regarding flags and symbols and to