World number one Novak Djokovic has become the latest tennis player to test positive for Covid-19.

It comes after Grigor Dimitrov, Borna Coric and Viktor Troicki all revealed they had coronavirus after playing at Djokovic's Adria Tour competition.

Djokovic, 33, played fellow Serb Troicki in the first event in Belgrade.

The remaining Aria Tour events in Banja Luka and Sarajevo have now been cancelled, Djokovic's brother Djordje has confirmed.

"Unfortunately, due to all the events that happened in the last few days, we have decided that the most important thing right now is to stabilise the epidemiological situation, as well as for everyone to recover," said Djordje Djokovic, who is a director of the tournament.

Britain's Andy Murray said the positive tests were a "lesson for us", while Australian Nick Kyrgios called playing a "bone-headed decision".

A statement on Djokovic's website said: "Immediately upon his arrival in Belgrade [after the second event] Novak was tested along with all members of the family and the team with whom he was in Belgrade and Zadar. He is not showing any symptoms."

There have been no ATP Tour events since February because of the global pandemic and the Adria Tour, which is not an ATP Tour event, was one of the first competitions to be staged since then.

The first leg in Serbia attracted 4,000 fans, and players were later pictured dancing close together in a Belgrade nightclub.

Bulgaria's Dimitrov played Croatia's Coric on Saturday in the second leg in Zadar, Croatia.

With Croatia easing lockdown measures, players were not obliged to observe social distancing rules and were seen embracing at the net at the end of their matches.

Pictures on the tournament's social media site from Friday showed Dimitrov playing basketball with Djokovic, Alexander Zverev and Marin Cilic, while he also put his arm around Coric before their match.

Zverev, Cilic and Andrey Rublev, who also played in the Adria Tour, have tested negative, but suggested they will all now self-isolate for up to 14 days.

The ATP Tour season is set to restart on 14 August and the US Open will be held without fans from 31 August to 13 September, despite some players voicing concerns about travelling to New York.

I am extremely sorry for each individual case of infection - Djokovic's statement

The moment we arrived in Belgrade we went to be tested. My result is positive, just as Jelena's, while the results of our children are negative.

Everything we did in the past month, we did with a pure heart and sincere intentions. Our tournament meant to unite and share a message of solidarity and compassion throughout the region.

The Tour has been designed to help both established and up and coming tennis players from South-Eastern Europe to gain access to some competitive tennis while the various tours are on hold due to Covid-19.

It was born with a philanthropic idea, to direct all raised funds towards people in need and it warmed my heart to see how everybody strongly responded.

We organized the tournament when the virus has weakened, believing the conditions for hosting the Tour had been met.

Unfortunately, this virus is still present, and it is a new reality we are learning to cope and live with. I am hoping things will ease with time so we can all resume lives the way they were.

I am extremely sorry for each individual case of infection. I hope it will not complicate anyone's health situation and everyone will be fine.

I will remain in self-isolation for the next 14 days, and repeat the test in five days.

Prayers up to all the players that have contracted Covid - 19. Don’t @ me for anything I’ve done that has been ‘irresponsible’ or classified as ‘stupidity’ - this takes the cake. https://t.co/lVligELgID

— Nicholas Kyrgios (@NickKyrgios) June 23, 2020