The NRL has fined the Manly Sea Eagles $750,000 for breaches of the salary cap over the past five years, while two officials have also received 12-month bans.

Of that amount, $250,000 will be suspended if the club undertakes appropriate governance changes to ensure there is no repeat of the breaches.

A $660,000 penalty will be applied to the club's salary cap for this season, and next year, meaning the club will be operating at a cap of $9 million.

Manly chief operating officer Neil Bare and former chief executive officer Joe Kelly, who is now the boss at the Sydney Roosters, have been suspended until January 1, 2019.

The breaches involve 15 players over five years, totalling $1.5 million.

No competition points have been deducted, because their squad is now compliant with the cap.

Sea Eagles coach Trent Barrett was given an official warning.

NRL chief Todd Greenberg
PHOTO: NRL CEO Todd Greenberg said the penalties were a warning to all clubs. (AAP: Dan Himbrechts)
NRL chief executive officer Todd Greenberg said the penalties were a warning to all clubs.

"The investigation found a number of cases where players were offered undisclosed benefits outside the salary cap to attract them to the club," Greenberg said.

"These benefits were in the form of third-party agreements which were never declared to the salary cap auditor.

"In other words, Manly had a financial advantage in securing the services of players who may otherwise have gone to other clubs."

The investigation into Manly's breaches was conducted by the NRL's integrity unit in which more than 800,000 documents, emails and text messages were examined.

It began in July 2017, after Manly invited it. The club was issued with a breach notice in December last year.

The club and officials are able to appeal the sanctions.

Manly legend Bob Fulton, who is one of the NRL's eight "immortals", did not make himself available during the investigation.

He resigned as the Sea Eagles' general manager of football last year, and was formally a national selector, however his term expired after last year's World Cup in Australia.

If he wants to return to the game in an official capacity, he will need NRL approval.

"It's fair to say that Bob was heavily engaged with negotiations for the period of time that he worked with Manly," Greenberg said.

"He's not a registered official with rugby league.

"The integrity unit reached out to Bob on numerous occasions.

"My understanding is that he was unavailable for interviews at the times they were requested."