SYDNEY — A Sydney lab has told hundreds of people they did not have Covid when they in fact had tested positive, amid soaring infections in the area, BBC reported.

The mistake, which took place over the Christmas period, was due to a "data processing error".

The Australian state of New South Wales is seeing rising infection numbers following the arrival of the hyper-infectious Omicron Covid variant.

Officials say an increase in swabbing tests has caused massive backlogs.

Some of those affected have expressed concern that they may have unknowingly infected their loved ones over Christmas.

The SydPath lab apologized in a statement on Tuesday and said the mistake, which affected 886 people in total, had happened as workers faced an "unprecedented" volume of tests.

It initially admitted earlier this week that it had erroneously told 400 people on Christmas Day that they did not have Covid. They were only notified about the mistake the following day.

The blunder grew when SydPath later revealed that hundreds more had been prematurely told they had tested negative, when their results had not yet been determined. On Tuesday, the lab said 486 people from this group had been confirmed as Covid-positive.

In its latest statement, SydPath said it had moved from an automatic system to a manual one to deal with its increased workload.

"Unfortunately... a simple data processing error was made which led to the wrong test results being released," it said.

SydPath said it had since switched back to its automated system and would reduce the number of Covid swabs it would process to maintain the quality of its testing.

Sydney resident Stephanie Colonna, who was one of those affected, told the Today Show she was now worried about her family. "That's what scares me and worries me. If (my niece and nephew) are positive, I'm the one to blame because I've infected them now," she said.

NSW Health Minister Brad Hazzard said the mix-up had emerged as pathology labs were "exhausted", according to the Australian Broadcasting Corporation.

Testing services in NSW have been struggling with high demand. Many have reported being turned away at clinics which had reached full capacity, while others have complained of long waits for test results.

The seven-day average for Covid tests in NSW has been around 145,000 swabs a day, up from 117,000 per day compared to the week before.

The NSW government has also had to reinstate some Covid restrictions, which had been lifted earlier in December.

Separately, police in South Australia have charged a 19-year-old who is accused of ignoring a directive by health authorities to isolate. He had visited a nightclub in Adelaide despite testing positive for Covid.