MELBOURNE (REUTERS) - Victoria health officials believe 520 players and support staff connected with the Australian Open are at relatively low risk of having been exposed to the new coronavirus by a Melbourne quarantine hotel worker who tested positive for Covid-19.

Play in the warm-up tournaments at Melbourne Park on Thursday (Feb 4) was cancelled after the case was announced late on Wednesday and the 520 who underwent quarantine at the Grand Hyatt hotel were instructed to get tested and isolate until they have a result.

At a Victoria government briefing on Thursday morning, officials said the tennis-related people would have dedicated testing facilities and were considered "casual contacts" of the hotel worker.

"We think the risk to other guests in the hotel - tennis players and their accompanying staff - is relatively low because they were in the room at the time as opposed to staff outside the room," Chief Health Officer Allen Cheng told reporters.

"The last person to leave, the last case to leave the health hotels left on Jan 22nd, so that is now getting close to 14 days since that time.

"So, if there was any exposure, they would be coming up to that period. So we think that risk is relatively low, which is why we are testing them to be sure, but it is precautionary."

The Australian Open is scheduled to begin next Monday and Victoria's Premier Dan Andrews said he thought the positive test - the first locally-acquired case in the state for almost a month - was not a threat to the tournament.

"I think we all understand that there are no guarantees in any of this," he said.

"But at this stage, the tennis shouldn't be impacted by this. These things can change (but) this has been a textbook response to this."

Tennis Australia spent millions of dollars to quarantine around 1,200 players, coaching staff and officials for 14 days in Melbourne from the middle of last month in order to get the Grand Slam underway.

Most players were allowed five hours outside for training but 72 were confined to hotel rooms for the two weeks after passengers on the charter flights that brought them to Australia tested positive for the novel coronavirus.

Most cleared quarantine last weekend and were involved in six events at Melbourne Park, including the ATP Cup, designed to offer them some match practice before the hard-court Grand Slam.

Organisers, who have plenty of experience reorganising matches because of rain, hot weather and last year's bushfire smoke, said a schedule for Friday's play would be released later on Thursday.