The Canterbury Bulldogs have been slugged with a $50,000 fine for allegedly failing to follow the NRL biosecurity protocols and take measures to ensure their players comply.

The protocols, which kept the 2020 season alive and are currently doing the same for the current one as an outbreak of COVID grips Australia, must be followed by all members of a club, including players and staff, who are listed on the Apollo register.

The NRL announced on June 17 that all members were barred from attending venues which weren't essential within the Eastern Suburbs of Sydney.

On June 20 however, five Canterbury players - Dylan Napa, Brandon Wakeham, Corey Waddell, Sione Katoa and Aaron Schoupp - attended the Coogee Bay Hotel and Royal Hotel in Bondi.

All five players have also been hit by breach notices by the NRL and will need to spend 14 days in isolation, even if they return negative coronavirus tests.

This is a New South Wales government health order, as they are deemed close contacts to a case.

It means all five players will miss the Bulldogs' upcoming game with the Manly Sea Eagles.

It's an unwanted blow for the Bulldogs, who will be scrambling to find 17 fit players for the game with Manly. The club already sit second-last on the competition table.

The NRL, in serving the breach notice and fines to the players, took into account the salaries of the players and the club's alleged poor communication.

The fines are as follows:

Dylan Napa - $5000
Brandon Wakeham - $1750
Corey Waddell $1500
Sione Katoa $1250
Aaron Schoupp $250

NRL CEO Andrew Abdo said the breaches were unacceptable.

"Our biosecurity protocols are the most important part of the competition, they are our licence to continue playing during the pandemic," he said.

"All clubs and players have a responsibility to ensure they comply with the rules to keep themselves and the community safe.

"In this instance we believe the Bulldogs failed to ensure the upgraded protocols were clearly explained to their players.

"This sanction sends a clear message to every club that you must do everything possible to ensure players understand the protocols.

"The players also have an obligation to seek further information if they are unsure of the upgraded biosecurity advice.

"Given the breach took place several days after the upgraded protocols had been communicated, we believe a sanction upon the players is also appropriate. In issuing the sanctions, we have taken into account that the players had a degree of confusion about the protocols."

Canterbury and the fined players will have five days to respond to the breach notice under NRL rules, should they wish to contest.