Tension between Brisbane and Cronulla escalated beyond the issue of Jack Bird's defection on Thursday, with the Broncos lodging a complaint to the NRL about the premiers.

The Broncos were furious the Sharks took it upon themselves to announce Bird was leaving Cronulla to link with Wayne Bennett at Red Hill before the NSW representative had signed the four-year contract with Brisbane.

Brisbane-bound: Cronulla's Jack Bird. Credit:John Veage

There is an unwritten agreement between NRL clubs not to divulge information about which club departing players have signed with, but the Sharks failed to observe that when they sent out a press release on Thursday afternoon confirming Bird was heading north of the border in 2018. "Our club has today been advised that regardless of our best efforts to retain him, Jack Bird has accepted a multi-year contract at the Brisbane Broncos," the Sharks statement said. "Despite our club making its highest ever financial offer to secure a current player, it could not match the multimillion-dollar deal offered to Bird to join the Broncos."

The Sharks didn't break any rules with their press release, but it left a few noses out of joint at the NRL, which wasn't impressed that the reigning premiers announced the Broncos deal without the consent of the club.