Newcastle chief executive Ken Conway confirmed the club had re-opened discussions with MacDougall and the 28-year-old would not be involved with the Knights until those talks had been resolved.
"He won't be training or playing with us until those discussions are finished," Conway said tonight.
"I'm not prepared to comment on the negotiations at this point. We have the right and Adam has the right to keep them private.
"I don't want to pre-empt the outcome."
MacDougall was granted a medical clearance last week to resume playing amid rumours he was about to be released by the Knights. The former NSW winger is on a contract worth about $300,000 a season, but suffered a major knee injury last season.
He played just one match in 2002 and is yet to take the field in 2003.
MacDougall was expected to make his return this weekend, but it's understood he may have played his last game with the club, who are struggling to fit all their off-contract players under the salary cap.
If he is granted a release from his contract - which expires at the end of next season - at least one rival club is known to be interested in recruiting the barnstorming winger.
MacDougall's manager George Liolio was unavailable for comment.Like