Israel released some 200 Palestinian security prisoners on Thursday, among them one of Hamas' founders and top leaders in the West Bank, Sheikh Hassan Yousef, who has been imprisoned over the past five years for his involvement in terror activities.

Israel Prison Service said it released the security prisoners as a gesture in honor of the holiday of Ramadan.

Open gallery view Senior Hamas leader in the West Bank Sheikh Hassan Yousef. Credit: AP

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Sheikh Hassan Yousef is considered one of the most prominent Hamas figures in the West Bank, and was one of the organization's founders. He was previously due to be released within a month and a half.

The story of Sheikh Hassan Yousef's son Mosab Hassan Yousef, who supplied intelligence to Israel's Shin Bet, has been extensively reported on by Haaretz.

Mosab Hassan Yousef served for over a decade as the Shin Bet security service's most valuable source in the Hamas leadership, going by the nickname "the Green Prince." The intelligence he supplied Israel led to the exposure of a number of terrorist cells, and to the prevention of dozens of suicide bombings and assassination attempts on Israeli figures.