An opposition group says a top Bahraini opposition leader has been released from prison after more than four years in custody.

The WAAD (National Democratic Action Society) group confirmed on its official Twitter account that Ibrahim Sharif was released Friday.

Sharif was leading WAAD at the time of his arrest in March 2011 and was one of the top leaders in the Feb. 14, 2011 uprising in Pearl Roundabout.

Sharif was sentenced in June 2011 to five years in prison for plotting to overthrow Bahrain's 200-year-old monarchy.