Belgian player Alison Van Uytvanck, who reached the Australian Open's second round, tested positive for COVID-19 before trying to fly home from Melbourne.

Belgian tennis player Alison Van Uytvanck has revealed she tested positive for COVID-19 after playing at the Australian Open.

The world No.55, who bowed out in the second round, joins Frenchman Ugo Humbert as players who have contracted the virus during the first grand slam of the year.

Van Uytvanck beat Spanish qualifier Cristina Busca in the first round before falling to China's Qiang Wang.

"My exit test in Melbourne to go back to Belgium came back positive," Van Uytvanck posted on Instagram on Sunday.

"I'm isolating and following all of the requirements.

"I have very mild symptoms and looking forward to be back even stronger."

The Open's COVID-19 testing program has attracted criticism from several high-profile players, including outspoken local Bernard Tomic, who failed to qualify for the main draw and tested positive days later.

After Humbert revealed he tested positive, men's third seed Alexander Zverev said he believed more players at the tournament had contracted the virus without being detected.

All players were tested on arrival in Australia and again between days five and seven of their stay.

Players who show symptoms face mandatory testing, while ongoing testing is optional for players without symptoms.

"So far it's worked well and it's been successful," Open boss Craig Tiley told the Nine Network.

"We're continuing with not only that testing program but also the physical distancing and the wearing of masks - you can see in the player area all the players have masks on.

"We're constantly reminding them around hygiene and how they stay safe and not only keep themselves safe but ensure that we keep Victorians safe, because that's been our goal from the beginning."