The finger pointing over the visa bungle that left world No.1 Novak Djokovic locked in a quarantine hotel and facing deportation continued on Friday.

Djokovic will remain in the Melbourne hotel, which also houses around 30 refugees, for another three days until his legal challenge resumes in the Federal Court on Monday.

The nine-time Australian Open champion is challenging the Australian government's decision to cancel his visa and issue deportation orders.

Prime Minister Scott Morrison on Thursday said Djokovic had tried to enter the country without a medical exemption from vaccination.

The Serbian claimed he had such an exemption, but it appears this was only granted for the tournament by TA and the Victorian government, and not entry into Australia.

The Department of Health sent TA boss Craig Tiley two letters in November stipulating that a COVID infection in the past six months would not satisfy entry requirements for unvaccinated players.

This is believed to be Djokovic's grounds for an exemption from vaccination.

Acting Victorian Premier Jacinta Allan said on Friday that TA didn't inform her government that a prior infection wouldn't be accepted.

"I'm advised that Victorian government officials had not seen that correspondence," Allan said.

"It reinforces that point that it is the Commonwealth government ... that's responsible for issuing visas and how they engage in that dialogue with bodies like Tennis Australia is a matter for them."

Allan said her government could only assess the eligibility of a medical exemption for players wanting to take part in the tournament after arrival into the country.

"That is very much separate from the visa process," Allan said.

This came as the Australian Open was dealt a further blow as Home Affairs Minister Karen Andrews revealed two other international arrivals were being investigated after travelling to Australia in similar circumstances for the Open.

"I can confirm the Australian Border Force is conducting its inquiries ... I am aware that there are two individuals currently being investigated by Australian Border Force," Andrews told Channel Seven.

Andrews said anyone entering Australia had to show evidence of vaccination or medical reasons why they are not vaccinated.

"We do have the intelligence to indicate there are some individuals here now that have not met the entry requirements and we have to investigate that," Andrews said earlier on the Nine Network.

"I know there is a lot of chatter about the visa. The visa, on my understanding, is not the issue, it is the entry requirement.

"The Border Force has been very clear that he (Novak) was not able to meet the requirement to provide the evidence he needed for entry to Australia."

Beyond the quiet of Djokovic's hotel, the outcry in his native Serbia is growing with his family saying he had been "held captive" and insisting the treatment of one of sport's greatest performers was a disgrace.

His family complained about the hotel as around 300 fans held a rally in front of the country's parliament building in the capital Belgrade,

"It's just some small immigration hotel, if we can call it a hotel at all. Some bugs, it's dirty, and the food is so terrible," Djokovic's mother Dijana said in a press conference.

His father Srdjan promised the crowd the protests would be held every day until Djokovic was released.

Nearer to home, former Davis Cup player Paul McNamee who ran the Australian Open from 1995 until 2006 as tournament director, joined those who think the 34-year-old deserved his day on court, not in court.

"It's not fair. The guy played by the rules, he got his visa, he arrives, he's a nine-time champion and whether people like it or not he's entitled to fair play," McNamee told ABC News.

"There's no doubt there's some disconnect between the state and the federal government.

"I hate to think politics are involved but it feels that way."

Australian Associated Press