In a now-deleted Instagram post, Moran called the Queen a "dumb dog" in the wake of her death.

"Today's a good fucking day, uncle Luke announces his tour, and this dumb dog dies, Happy fucking Friday," the Newcastle Knights player wrote.

The "dumb dog" was understood to be in reference to the monarch - for whom Australia is holding a national day of mourning on September 22 - and "uncle Luke" country singer Luke Combs.

The NRL Integrity Unit was alerted to the post and has issued Moran with a fine worth 25 per cent of her contract - which will be suspended for 12 months - and a one-match ban.

Moran has five days to accept the sanction or challenge it.

"There will be a further requirement that Moran attend such education and training as is recommended by the NRL's Wellbeing and Education Department, in consultation with the Australian Rugby League Indigenous Council, concerning her responsibilities as a player and the appropriate use of social media," said the NRL in a statement.

"Rugby league is an inclusive game and has a proud and strong relationship with many communities.

"Regardless of any personal views, all players and officials must adhere to the professional standards expected of them and on this occasion, the public comments made by the player have caused damage to the game."

Ronald Griffiths, head coach of the Newcastle Knights, defended the player, citing issues indigenous Australians have with the monarchy.

Both Moran and Griffiths are indigenous.

"The relationship between indigenous people and the monarchy is a complicated one," Griffiths said in comments widely reported by the Australian media.

"If Caitlin has done something then it will be investigated by the Integrity Unit and we'll work our way through the process.

"We're talking a little bit of negativity with Caitlin, but if we look at we're she's come from, in 2017 she wins us the World Cup and does her knee the year after and has probably in the wilderness since then."

The Queen's reign lasted 70 years from 1952 until last Thursday (September 8).

King Louis XIV of France is the only monarch to have ruled for longer.

Queen Elizabeth II's period as head of state for Australia covered some of the time of the Stolen Generations, when Aboriginal and Torres Strait Islanders children were forcibly removed from their families by the Australian Government.