Cameroon international Alexandre Song has signed what Arsenal describe as a “long-term” contract with the London club.
The Cameroon international, who has six caps to his name, favours a holding midfield position but played at centre-back for the last five matches of the 2007-08 Barclays Premier League season.
Song, 20, originally joined Arsenal from French club Bastia on a season-long loan deal in 2005.
He then signed a permanent contract with the Gunners the next summer before being loaned out to Charlton for the 2006-07 season.
Song remained with the Arsenal squad last season, making 15 first-team appearances.