The 21-year-old signed a new five-year deal in September but is unhappy at St James' Park, with stories towards the end of the January transfer window linking him with a move to Tottenham.

"Charles came to talk to me about speculation that there was interest from Tottenham Hotspur," Keegan was quoted as saying in French newspaper L'Equipe.

"He has just signed a new contract but it's something we will have to look at again this summer because the signs are that he's not happy here."

N'Zogbia, a midfielder by trade, has started every match since Keegan's return to the club but has often found himself deployed at left-back.

Keegan's predecessor, Sam Allardyce, convinced N'Zogbia to extend his stay in the summer, despite the player previously expressing a desire to leave the club he joined from Le Havre in 2004.

He is believed to favour a move to London, where both his mother and sister live.