Novak Djokovic on Friday thanked people "around the world" for their support since he was dramatically refused entry to Australia over his Covid-19 vaccine status.

The Serb, who is in a Melbourne immigration detention facility pending an appeal, said on Instagram: "Thank you to people around the world for your continuous support. I can feel it and it is greatly appreciated."

Djokovic, an outspoken vaccine sceptic, was held after arriving in Australia this week to play in the Australian Open, where he was bidding to win an unprecedented 21st Grand Slam title.

The men's world number one's visa was revoked for failing to meet the country's tough pandemic restrictions, a development that has reverberated globally and sparked an angry reaction from Serbia.

Around 50 of his supporters -- a mix of tennis fans, anti-vaccine demonstrators and immigrant rights activists -- rallied in the rain Friday, the Orthodox Christmas, outside the detention facility in Melbourne where it is thought he is being held.

"We come out to support him just because it's our Christmas and obviously he's going through a lot," said fan Sash Aleksic.

The vaccine-sceptic tennis ace was detained on arrival in Australia earlier this week
The vaccine-sceptic tennis ace was detained on arrival in Australia earlier this week AFP / Marco BERTORELLO

"There would obviously be a lot more people here if people did not have family obligations today."

Not everyone was a supporter, though, reflecting anger at the case felt by many Australians, who have endured nearly two years of travel bans and rolling lockdowns.

"Refugees are welcome here, Djokovic is not," chanted a group of protesters. Police intervened to separate them from the Djokovic fans.

"We want to show that what Novak stands for is anti-public health, anti-social solidarity, and we stand for the freedom of refugees who've been held for eight-plus years," said Zak Barzovoy, a 27-year-old student.

The former Park Hotel, now officially known as an "alternative place of detention", holds about 32 refugees and asylum seekers trapped in Australia's hardline immigration system.

The five-storey centre gained notoriety last year when a fire forced migrants to be evacuated, and maggots were allegedly found in the food.

Police stand guard at the government detention centre in Melbourne where Djokovic is staying
Police stand guard at the government detention centre in Melbourne where Djokovic is staying AFP / William WEST

Djokovic's family have said the hotel is "dirty".

Foreigners are still mostly banned from travel to Australia, and those granted entry must be fully vaccinated or have a medical exemption.

Djokovic said he had secured an exemption to play in the Australian Open this month, but the Australian government said he did not meet the stricter standard required to enter the country.

Australian authorities said the 34-year-old star provided no evidence of an exemption and was detained, pending deportation.

Djokovic's stance on the Covid vaccine has raised questions about his participation in other major tournaments this year.

In a series of fiery remarks, Srdjan Djokovic told a crowd in Belgrade that his son was the victim of a "political witch hunt"
In a series of fiery remarks, Srdjan Djokovic told a crowd in Belgrade that his son was the victim of a "political witch hunt" AFP / ANDREJ ISAKOVIC

But France's sports minister said her country would allow him to play in the French Open, the next Grand Slam tournament of the year, which starts in May, even if he was not vaccinated.

"There are health protocols imposed for major events by the relevant federations which would permit someone like Novak Djokovic to enter the country," Roxana Maracineanu said.

"In France today we do not have the same regulations as Australia for entry to the country, either for athletes or any citizens from other countries," she added.

Another player due to take part in the Australian Open, Czech player Renata Voracova, has had her visa cancelled and is in the same facility as Djokovic, her government said Friday.

"They bring me food and there's a guard in the corridor. You have to report, everything is rationed. I feel a bit like in prison," 38-year-old Voracova told Czech media.

Djokovic's father Srdjan told a crowd in Belgrade his son was the victim of a "political witch hunt".

"Jesus was crucified and endured many things but is still alive among us," he said in a fiery speech. "Novak is also crucified... the best sportsman and man in the world."

On Friday, he slammed Australian Prime Minister Scott Morrison calling him a "big villain".

Djokovic's detention has sparked international scrutiny, with the Serbian government demanding explanations.

"Djokovic is not a criminal, terrorist or illegal migrant, but was treated that way by the Australian authorities which causes an understandable indignation of his fans and citizens of Serbia," a foreign ministry statement said.

The country's president, prime minister and foreign minister have issued a series of nationalist-tinged remarks brimming with anger at the treatment of the national hero.

Morrison has defended revoking Djokovic's visa.

"Rules are rules and there are no special cases," he said.

Tennis players seemed divided, but some rallied around the star.

"Look I definitely believe in taking action, I got vaccinated because of others and for my mum's health, but how we are handling Novak's situation is bad, really bad," said Australian star Nick Kyrgios on social media.

Although Djokovic won a legal reprieve from deportation until at least Monday, when his attempt to overturn his visa cancellation will be heard in court, it is unclear whether he will play in the January 17-30 tournament.

Judge Anthony Kelly warned the star's lawyers in a hearing Thursday that justice would move at its own pace through all necessary appeals. "The tail won't be wagging the dog here," he said.