The tennis world number one is in immigration detention following the cancellation of his visa on Thursday, hours after he arrived at Melbourne airport.

The 34-year-old Serbian said in his court application he had a valid visa and medical exemption from the organiser of the Australian Open - a tournament the defending champion is hoping to compete in later this month.

Why is Djokovic being denied entry to Australia - and what are their travel rules?

Two other people connected to the Australian Open voluntarily left the country after being told to do so by border officials.

One of them is Czech player Renata Voracova, whose visa was also revoked due to issues with her exemption.

Djokovic, an outspoken critic of mandatory vaccination, is currently embroiled in a row over whether he is exempt from the country's COVID inoculation rules.

Djokovic 'told he met travel requirements'

The application says he received a document from the Department of Home Affairs on 1 January telling him he met the requirements for quarantine-free travel into Australia.

Djokovic's lawyers said he received an exemption certificate from Tennis Australia, which was "provided by an Independent Expert Medical Review panel" whose decision was endorsed by the Victorian state government's own medical exemptions panel.

Reports say Tennis Australia told unvaccinated players they may be able to obtain a temporary exemption if they had recovered from COVID in the past six months, according to a leaked letter.

Tennis Australia 'did not mislead players'

Tennis Australia said it had not knowingly misled players and had always urged players to get vaccinated.

The guidance issued was based on information on a national government website to which it had been referred by the federal health minister, the association said.

"We have always been consistent in our communications to players that vaccination is the best course of action - not just as the right thing to do to protect themselves and others, but also as the best course of action to ensure they could arrive in Australia," Tennis Australia said in a statement quoted by local media.

Federal government denies responsibility

News Corp media outlets said the association distributed its guidance last month.

However, the federal government released a letter showing it wrote to Tennis Australia in November saying that a previous COVID infection was not necessarily grounds for exemption in Australia, as it is in some other countries.

The date Djokovic said he tested positive for coronavirus - 16 December - was the same day he was presented with a stamp by the Serbian national postal service at the PTT Museum in the capital Belgrade. He tweeted about the presentation the following day.

The tennis player will argue for his visa to be reinstated at a court hearing on Monday.

Meanwhile, the Ministry of Foreign Affairs of the Czech Republic said they sent a diplomatic note to Australian authorities and are waiting for a reaction.

Voracova's decision to leave was "not based on grounds of deportation", they said, adding that it was her "own decision" to stop participating in the tournament.