Sky Sports sources understand that Newcastle captain Kevin Nolan has rejected a new contract, while Alan Smith has been told he can leave St James' Park.
Nolan, who has two years left on his current terms, is understood to have been offered a new deal two weeks ago.
But it is reported that the 28-year-old turned down Newcastle's offer of a two-year extension because he wanted an improved five years.
The club's manager, Alan Pardew, will worried by Nolan's decision, which comes in the wake of Joey Barton's refusal to commit his long-term future.
At the same time, Pardew is continuing to reshape the squad he inherited after taking over in December and he has told Smith that he is free to look for a new club.
The 30-year-old played just 14 matches last season after suffering from injury and losing his place in the team to Cheik Tiote.
News of Smith's departure could interest West Ham and their new boss, Sam Allardyce, who took the player to Newcastle when manager in 2007.
Pardew also released Sol Campbell and Shefki Kuqi in May as he looks to build a squad capable of competing for a place in Europe next season.