Tennis star Novak Djokovic has admitted he is an anti-vaxxer and it may lead to a delay in his return to the sport.

The World No 1 said in a Facebook live with other Serbian athletes he would not want someone to force him to have a vaccine.

"Personally I am opposed to vaccination and I wouldn't want to be forced by someone to take a vaccine in order to be able to travel.

"But if it becomes compulsory, what will happen? I will have to make a decision.

"I have my own thoughts about the matter and whether those thoughts will change at some point, I don't know.

"Hypothetically, if the season was to resume in July, August or September, though unlikely, I understand that a vaccine will become a requirement straight after we are out of strict quarantine and there is no vaccine yet."

The tennis season is suspended until at least July 13 with Wimbledon being cancelled for the first time since the Second World War.