Southend United have rejected a bid from Colchester United for defender Adam Barrett.
An undisclosed six-figure offer was made for the centre-half, who was a free transfer signing from Bristol Rovers three years ago.
Colchester's bid for Barrett has been given short shrift by Ron Martin, with the Southend chairman insisting the player is not for sale.
"Under no circumstances will Adam Barrett be leaving the football club," he told the club's official website.
"I'm surprised Colchester have made an offer, and then gone one step further by publicising it.
"It's nice to know that our players are atrracting offers from other teams.
"But our focus is on promotion and that will not happen by weakening our squad."