The decision follows the NRL's investigation into the behaviour of Okunbor and Harawira-Naera during the Bulldogs' preseason trip to Port Macquarie in February, when they brought two young women back to the team's hotel.

The NRL's show-cause process found the behaviour of each player "constituted very serious breaches" of the code of conduct.

NRL chief executive Todd Greenberg said the league wanted to send a strong message about the off-field behaviour of players.

"The behaviour of both players was inexcusable and a very serious breach of the code of conduct,'' he said in a statement.

"The game will not tolerate such conduct and as such both players have had their registrations cancelled.

"This decision should send a very clear message to all players of our stance on such behaviour."