John O'Shea has signed a three-year contract extension at Manchester United which keeps him at Old Trafford until 2012.

The Republic of Ireland defender has been at the club since 1999 when he arrived as a trainee. "John has developed in his years here and is now regarded as one of the more experienced players," said Sir Alex Ferguson, the United manager.

"He has proved through his personality and professionalism he is an outstanding credit to the club and I am delighted he has signed a new contract."

Although the Waterford-born player has rarely been a regular starter for Ferguson, he has proved to be an integral part of the United squad at either centre-half, full-back or in central midfield, playing over 250 games for the club, and his late goals against Liverpool and Everton on Merseyside last season were viewed as major factors in United's Premier League title success.

With Nemanja Vidic also recently signing a new deal and negotiations taking place with Patrice Evra and Wes Brown, it is clear Ferguson is still building for the future.

"I am extending my contract with the champions," O'Shea said. "I have been at the club since the age of 17 and it is a dream come true to play for such a great club.

"I hope to play my part in bringing more trophies to the club and to continuing the success with this young, exciting team.

"I would like to thank the boss, the staff and the fans for their continued support."