Thousands of cricket fans who attended Australia's showpiece Boxing Day Test against India have been told to get tested and isolate, after a spectator at the match tested positive for Covid-19, AFP reported.

Health authorities said the man in his thirties was not infectious while at the famed Melbourne Cricket Ground on the second day of play “but there is potential he acquired the virus while there” or at a nearby shopping centre.

“The MCG is being investigated as a potential source for the infection,” Victoria's Department of Health said.

“We're encouraging anyone who was in The Great Southern Stand, zone 5 of the MCG between 12.30pm and 3.30pm on 27 December, to get tested and isolate until they receive a negative result,” health authorities said.