The NRL was advised late on Thursday night that prop Dylan Napa, halfback Brandon Wakeham and centre Aaron Schoupp attended The Royal Hotel in Bondi last Sunday, which was attended by a person who has tested positive to COVID-19.
Canterbury's squad will not train until the test results of the three players are known. The players have not been in contact with representatives from any other club nor does it impact any State of Origin player.
ARL Commission chairman Peter V'landys said an investigation into the Bulldogs trio would be finalised before sanctions were considered and praised other players who had followed COVID-19 protocols.
"They have got to be given due process and natural justice," V'landys told 2GB.
"The good thing is that they used their QR codes when they went to these premises, so they did the right thing there.
"There are 800 players and officials in our bubble and last year they proved how professional and conscientious they were and there was no breach, so I just hope that nobody judges them on just one breach because the players have done a wonderful job on keeping the competition going.
"Their professionalism is not in doubt so this one breach, it is regrettable but I hope people don’t judge it as a whole."
The NRL issued a clear directive to all Sydney-based clubs on June 17 that players and staff were not to attend any restaurants, clubs or bars in the Waverley Local Government area.
All clubs in the Greater Sydney, Wollongong and Central Coast areas were placed on level-three biosecurity protocols from Tuesday evening and are not permitted to leave home except to train or access essential services.
The NRL issued a statement to say it will continue to seek advice from its biosecurity experts and NSW Health to ensure no risk to other teams or the community.
On Friday afternoon it was announced that ARLC chairman Peter V’landys and NRL CEO Andrew Abdo are set to miss this weekend’s State of Origin fixtures after deciding to return to Sydney in support of COVID-19 protocols.
V’landys and Abdo will depart Brisbane while other NRL staff impacted by the public health orders are set to be confined to their hotels except while working at the Origin matches on Friday night at Sunshine Coast Stadium and Sunday night at Suncorp Stadium.
"We are coming back as I work in the CBD and Andrew is in Randwick," V’landys told NRL.com.
"Accordingly, under the new Queensland protocols we will be required to follow the NSW protocols and stay in our rooms. We thought we would lead by example in following the protocols."
NSW Premier Gladys Berejiklian on Friday morning announced anyone who lives or has worked in four Eastern Sydney local government areas over the past 14 days - Woollahra, Waverley, Randwick and the City of Sydney - would only be allowed to leave home to travel for necessary work or education, participate in outdoor exercise, to care for a relative or buying essential goods or services.
The order is due to begin at 11.59pm AEST on Friday, running until 11.59pm next Friday.
The Queensland Government announced that anyone from NSW who had entered the state was expected to abide by the protocols as they would if they were at home.
NSW Origin players, who arrived in Brisbane on Friday, will enter a COVID-19 bubble from 1am Saturday, while Level 3 biosecurity protocols will be imposed at Suncorp Stadium on Sunday night.
This includes temperatures tests for players on arrival at the stadium and the implementation of clean and dirty zones inside the venue.
All players and staff from Sydney-based NRL teams have been living under Level 3 restrictions since June 17 and clubs were told on Friday that those protocols would remain in place when they return to training next week.
Wests Tigers on Friday afternoon said their Round 16 match against South Sydney would be played before a reduced crown at Leichhardt Oval.
"Due to current changes to venue capacities, the club will be providing a full refund to all current ticket purchasers for the fixture against the South Sydney Rabbitohs at Leichhardt Oval," the statement said.
Canterbury issued a statement on Friday morning to confirm the club had been advised by the NRL of the incident.
"The club has worked closely with the NRL to immediately self-isolate the players and send them for COVID testing. The results of those tests are expected sometime today.
"The club will release details of the results of those tests once they are known."
Canterbury, along with the other 15 NRL clubs, have a break this week due to the Ampol State of Origin series and are due to host Manly at Bankwest Stadium next Saturday.
The NSW Blues have had to recruit a new medical team based in Queensland for Origin II after doctors Nathan Gibbs and Paul Annett and physio Travis Touma were denied entry to the state due to COVID-19 travel restrictions.
Touma, who is the Sydney Roosters' high-performance manager, and Dr Gibbs, the Manly doctor, live in areas that had been deemed to be COVID hot spots, while Dr Annett was unable to fly north before the border closed on Thursday morning.
"We have had to find two new doctors and a physio," Blues adviser Greg Alexander said.
"Both doctors couldn’t make it and also Travis, one of physios and trainers who runs onto the field."
The families of many of the NSW players are also unable to attend the match at Suncorp Stadium on Sunday night.
The Roosters on Thursday moved their round-16 clash with Melbourne to Newcastle's McDonald Jones Stadium.
Penrith announced on Friday that they would be refunding tickets purchased for next Friday's showdown with Parramatta.
The Panthers said a reduced ticket allocation would be made exclusively available to 2021 members via a redemption process.
And the clash between the Lebanese Cedars and Malta at Belmore Sports Ground on Saturday has also been called off due to the NSW Public Health orders.