Manly prop Addin Fonua-Blake has been fined $20,000 for calling referee Grant Atkins "a f***ing retard" during a game on Sunday.

The money will be donated to Wheelchair Rugby League Australia and the NRL has also decided that Fonua-Blake will referee wheelchair rugby league games once biosecurity protocols allow "to gain a better understanding and respect of disability groups".

He was initially suspended for two weeks for the abuse of the referee at the end of the Sea Eagles' two-point loss to Newcastle, but the NRL found a breach of the league's anti-vilification code and decided to take further action.

NRL chief executive Andrew Abdo said he hoped the actions taken by the league would help drive change.

"The focus of this penalty is about rehabilitation and education, it's not punitive," he said.

"I see this as an opportunity to provide positive change for Addin and his experiences will also rub off on the broader playing group. Increasing the suspension is an easy decision but what is more important is driving change in attitudes."

Fonua-Blake apologised to the referees for his abuse on the day, and in a video released by the club, he said he was not aware of how derogatory the term was.

But Abdo said "ignorance is not an excuse".

"There is no tolerance for comments like we witnessed on Sunday," he said.

"Rugby league breaks down social barriers and gives everyone an opportunity to participate. Inclusivity is the foundation of our game."

Manly chief executive Stephen Humphreys released a statement saying Fonua-Blake and the club accepted the NRL's decision "without challenge or complaint".

In addition to concerns about vilification and discrimination, the NRL is also moving to stamp out further abuse of the officials.

Abdo said it was "unacceptable and will not be tolerated", flagging that he would recommend all matters of "serious abuse or intimidation of match officials" should be sent straight to the judiciary in future.

He said that would "ensure penalties meet community expectations".