The message stated they could cease isolation 12 hours earlier than the Department of Health and Human Services requires.

Barwon Health public affairs and communications director Kate Bibby said a message with advice from the health provider's COVID-19 monitoring team "was sent in error to the contacts".

"The message was sent 12 hours early due to an internal miscommunication. This was quickly resolved with a follow-up message," Ms Bibby said.

"We apologise for any confusion this caused to the people who received the advice at the wrong time."

Earlier: PEOPLE required to isolate for 14 days in Colac have been sent a text message saying they can cease quarantine too early, Polwarth MP Richard Riordan says.

Mr Riordan said he was "frustrated" on Friday to see residents had been sent the information, which came from Barwon Health's COVID-19 monitoring team.

The message said recipients had met "Department of Health and Human Service's criteria for cessation of quarantine" but was followed up by a second text message acknowledging it was sent in error.

The second message asked recipients to "please continue to isolate" until they received notice on Saturday marking the end of their quarantine.

Mr Riordan said the message was clearly sent "a day early" and he was " tired of mistakes being made".

"The people in lock up know what the rules are, but it just leads to people's lack of confidence," he said.

"What confidence do you have in the department running this when they are continuing sending out the wrong information at the wrong time."

It comes as Bulla Dairy Foods chief executive Allan Hood said the company had "no idea" about 10 additional cases the department linked to Bulla.

There are now 33 active cases in the shire, with multiple businesses impacted by the infected man, dubbed Colac's 'patient zero'.

There have been a total of 131 cases in Colac-Otway Shire to date.

READ MORE: