The San Diego Padres have released right-hander Mark Prior, whose once-promising career has been interrupted by two shoulder surgeries since April 2007.

Prior had signed a minor league contract with the Padres in January.

General manager Kevin Towers said the Padres didn't see enough progress with Prior's rehab to believe he could help the big league club this season.

Prior hasn't pitched in the big leagues since Aug. 10, 2006, while with the Chicago Cubs.