A Sydney laboratory has apologised after hundreds of people were told they had tested negative for COVID-19 when they were positive.
"SydPath last night incorrectly messaged more than 400 people, advising them they had tested negative to COVID," SydPath said in a statement.
"These people had tested positive to COVID.
"As soon we became aware of the issue this morning, SydPath immediately commenced a process to contact impacted people.
"An emergency response team is now investigating the cause of this mistake, which is believed to be human error.
"We sincerely apologise to all those impacted."
SydPath medical director Professor Anthony Dodds read out a statement to the media this afternoon.
"Owing to the very large volume of tests that we've been contending with at SydPath, last night we incorrectly messaged 400 patients who had been swabbed at our centres from December 22 and December 23 advising them they had tested negative to COVID-19," Professor Dodds said.
"These people had in fact tested positive to COVID-19.
"As soon as we became aware of this issue this morning, SydPath immediately commenced the process to contact these impacted individuals."
Professor Dodds said none of the sailors involved in the Sydney to Hobart yacht race are believed to be caught up in the cohort of infected people.