Walker was on holiday with Rabbitoh Aaron Gray. 

It is believed a man whose son was arrested in Phuket, notified the NRL integrity unit of the players’ behaviour.  

The Rabbitohs and the Sea Eagles are also investigating.

Walker and Gray were last season admitted to hospital after overdosing on prescription drugs.

Walker was fined $10,000 by Manly earlier this year for fracturing his hand while punching his apartment door. He missed three games.