Leadbitter, from nearby Fencehouses, scored two goals in 17 Premier League starts for the Black Cats last season and has impressed since Roy Keane arrived as manager in August 2006.

The midfielder, whose previous deal ran out in 2009, said: "I'm happy at the club and I want to help drive it forward next season, I want to kick on."

Sunderland boss Keane added: "Grant's done a good job since I came to the club. He's got quality and he's enthusiastic - a good character. He's maturing well."

Leadbitter is now Sunderland's longest-serving player after making his debut in September 2003.