East Jerusalem - Palestinian prisoner Bilal Kayed has been released after spending 15 years in Israeli jails, his family has confirmed.

His case caused outrage within the Palestinian community when he was placed under administrative detention on June 15 - the day he was due to be released after serving his full sentence.

Administrative detention is a military court order that allows Israel to detain Palestinians on "secret evidence" without trial or charge for renewable six-month intervals.

"We cannot express how happy we are that he has been released but it is an incomplete happiness because he carries the message of all the other prisoners who remain in Israeli jails," Kayed's brother Mahmoud told Al Jazeera on Monday.

"The hardest part was when he was transferred to administrative detention because we were preparing ourselves for his release, but he wasn't, which was extremely unjust."

Mass hunger strike

In protest against his detention, Kayed refused food for 71 days before reaching a deal with Israeli authorities to be released at the end of the six months.

Hundreds of other prisoners also expressed solidarity by participating in a mass hunger strike.

Muhannad al-Azza, a lawyer with the Jerusalem-based Addameer prisoner rights group, says "Kayed’s case was an exception.

"Normally, no one spends that much time in prison and is then placed under administrative detention. At least 250 prisoners went on hunger strike to call for his release," Azza told Al Jazeera.

Kayed refused food for 71 days before reaching a deal with Israeli authorities [Reuters]

Under international law, the use of administrative detention is permitted only in exceptional cases related to security.

Israel, however, has detained thousands of Palestinians for years without charging them or allowing them to defend themselves in trial.

Of the estimated 7,000 Palestinians behind Israeli bars, at least 720 are administrative detainees, according to Addameer's statistics.

In 2001, Kayed was imprisoned by the Israeli authorities at the age of 19 and served a fourteen-and-a-half-year sentence for his affiliation with the Abu Mustafa Brigades, the armed wing of the Popular Front for the Liberation of Palestine, a leftist political party.

"If he did not go on hunger strike, they would have renewed his administrative detention. Freedom is not served on a silver platter," said Azza.

Follow Zena Tahann on Twitter @Zenatahhan

Source: Al Jazeera News