Mullen tested positive to steroids in the off-season with the former NSW half still being paid a reported $50,000 a month.

Knights CEO Matt Gidley refused to confirm if the club would continue to pay him while his B sample is tested. 

The 30-year-old had sought to have the ban dropped which was unsuccessful.

“As we have said all along, this has been a disappointing matter for all parties,” Knights CEO Matt Gidley.

“We wish to reiterate this matter took place independently of the club.

“It is important to acknowledge Jarrod made a significant contribution to the club over a long period of time and that adds to the disappointment in how he now departs the club.

"He's devestated so it's important we consider Jarrod's well-being. While we are extremely disappointed in him we will continue to stand behind him from a well-being point-of-view.  

“We wish him and his family all the best for the future.”

Mullen played 211 games for Newcastle since debuting in 2005.