Four people were being questioned by police after a Russia flag with Vladimir Putin's face on was displayed at the Australian Open.

A small group of people gathered outside Rod Laver Arena following Novak Djokovic's quarter-final victory over Russian Andrey Rublev and were heard chanting 'Serbia, Russia'.

A man wearing a T-shirt bearing the pro-war Z symbol held up the Putin flag. A different man had been pictured with a Z T-shirt inside the stadium during the match.

A statement from Tennis Australia read: 'Four people in the crowd leaving the stadium revealed inappropriate flags and symbols and threatened security guards.

'Victoria Police intervened and are continuing to question them. The comfort and safety of everyone is our priority and we work closely with security and authorities.'

Organisers last week banned Russian and Belarusian flags from the venue for the duration of the tournament after one was held up at a match between Russian and Ukrainian players.

The letter 'Z' has become a symbol of ultra-nationalist obeisance to Russian president Vladimir Putin as he wages his war on Ukraine. It has been seen sprayed in white on the side of Russian tanks as they have invaded their neighbouring country.

Items of clothing that showcase a white letter 'Z' is among a list of prohibited items at the Australian Open.  

And Ukrainian tennis star Alex Dolgopolov has called for the spectator to be 'banned for life' after he removed a white T-shirt to display the war symbol in Melbourne.

'This guy will get banned for life, at least for all Australian events, right? @AustralianOpen,' he tweeted.

Outside the venue, footage emerged of fans waving flags plastered with Putin's face, despite tournament organisers banning Russian Federation and Belarusian flags at the event. 

The group were heard chanting songs in support of Russia, according to bystanders.

The issue of Russian flags being brandished at the tournament first reared its head last week, when a rogue fan hung up a Russian flag during a match between Ukraine's Kateryna Baindl and Russia's Kamilla Rakhimova.

Tennis Australia responded to the incident by immediately banning the display of Russian and Belarusian flags having already ruled that players from those countries must compete as neutral players 'without flags or country recognition'. 

In response Russia's embassy accused Open organisers, Tennis Australia, of polticising the event.

The embassy expressed the hope that Tennis Australia would instead aim 'to provide the best possible environment for the enjoyment of tennis'. 

Earlier, Ukrainian diplomat Mr Myroshnychenko took aim at the Open over a Russian flag being draped and clearly visible from an outside court during the match between Baindl and Rakhimova. 

'I strongly condemn the display of the Russian flag during the game of the Ukrainian tennis player Kateryna Baindl at the Australian Open today,' Myroshnychenko wrote on Twitter.

'I call on Tennis Australia to immediately enforce its 'neutral flag' policy.'

Mr Myroshnychenko earlier called for Russian and Belarusian players to be banned from the Open as they were from the last Wimbledon but Tennis Australia turned down the demand.