NRL CEO Andrew Abdo has promised action after Jack Wighton was targeted on social media by a member of the public following his decision to sign with the South Sydney Rabbitohs.

The star put pen to paper on a four-year deal with the Redfern-based outfit yesterday, ending his time at the Canberra Raiders from the conclusion of this season.

Likely the final contract of his career, it was the first time Wighton - who has played more than 200 NRL games for the green machine - has hit the free agency market.

The deal, believed to be for less money than what had been offered by both the Raiders and Dolphins, is likely to still come under the microscope of the NRL in the coming days, but a member of the public made a disgusting approach to Wighton on social media, shared in a screenshot by the five-eighth to his account.

"F*** off now you weak-gutted dog," the message to Wighton read in one part.

Wighton shared the screenshot with the caption "Stooping low here" and "for what reason little coward."

NRL players, including soon to be new teammate Cody Walker, rushed to the defence of Wighton, while CEO Andrew Abdo said the competition's integrity unit will investigate the incident and attempt to track down the perpetrator, according to Fox Sports.

โ€œIt's absolutely abhorrent that we have people that talk to anyone in that way, whether they are a footballer or a member of the public,โ€ Abdo said.

โ€œThe integrity unit will now investigate to try to track down the person and take the appropriate action.โ€