BETHLEHEM (Ma'an) -- Israel will be responsible for any permanent harm caused to prisoners on long-term hunger strike, a United Nations expert said Friday.

Mahmoud al-Sarsak, from Rafah in southern Gaza, has been on hunger strike for 82 days. A soccer player on Palestine's national team, he has been detained by Israel for nearly three years without charge and is demanding his release.

UN Special Rapporteur Richard Falk said Israel must present evidence to support charges against al-Sarsak or release him.

"Israel will be responsible if any permanent harm results," Falk added.

Al-Sarsak was briefly hospitalized on Thursday but was returned to Ramle prison clinic because Assaf Harofeh Medical Center decided he did not need to be admitted, a spokeswoman for the Israeli Prison Service Sivan Weizman told Ma'an.

On Wednesday, an independent doctor was allowed to visit al-Sarsak for the first time since he went on hunger strike after Physicians for Human Rights petitioned an Israeli court for access.

The doctor said al-Sarsak was at immediate risk of death. He has experienced extreme weight loss, frequently loses consciousness, suffers memory lapses and is at risk of life-threatening pulse disruptions, the doctor said.

He has not been allowed to see or speak to his family since his arrest in July 2009.

Falk also called for the release of Akram al-Rekhawi, who has refused food for 58 days.

Al-Rekhawi has been held at Ramle prison clinic since his arrest in 2004 and suffers chronic illnesses including diabetes and asthma.