NABLUS (Ma’an) -- The longest serving Palestinian prisoner being held under administrative detention is set to be released on Sunday, a prisoners center said.

Adnan Asfur, 50, has been held by Israeli authorities for over three years without being charged for a crime, director of Ahrar center for prisoners Fuad al-Khafsh said Saturday.

Asfur, from Nablus, was detained on March 9, 2009, and has been imprisoned for a total of six years during his life, having been arrested by Israeli forces on 16 separate occasions.

He participated in a mass hunger strike campaign by prisoners in April, when nearly 2,000 Palestinians in Israeli jails refused to eat in protest against prison conditions and administrative detention, al-Khafsh added.

Under Israel's administrative detention policy, prisoners can be held without formal charges for renewable periods of six months. Defendants and their lawyers are not given access to the evidence used to imprison them.

There are at least 300 people, including 22 members of the Palestinian Legislative Council, currently being held under administrative detention, according to Addameer prisoners group.