BETHLEHEM (Ma'an) -- President Mahmoud Abbas met Thursday with the United Nations envoy for the Middle East peace process to discuss the issue of Palestinian prisoners, a UN official said.

Robert Serry and Abbas met in Ramallah and discussed "issues of shared interest," including peace talks and the internal politics, a spokesman for the UN official said.

"In this context, there was a focus on the issue of Palestinian prisoners," Richard Miron said.

Abbas and Serry agreed on the urgency of resolving the issue immediately, Serry's office said, and the president expressed his appreciation for the United Nations' contribution.

Serry reiterated the concern of the UN, expressed a day earlier by UN chief Ban Ki-moon, who stressed "the importance of averting any further deterioration in their condition."

"(Ban) reiterates that those detained must be charged and face trial with judicial guarantees, or released without delay," he said through a spokesman Wednesday.

Abbas' meeting with Serry came a day after a group of protesters blocked the entrance to the UN office in Ramallah, slamming the world body for not intervening to save hunger-striking prisoners.

Protesters told Ma'an they wanted to disrupt a full day's work and would continue the action until the UN took a stand against Israel's violation of international law.

Hundreds of Palestinians in Israeli jails joined a hunger strike on April 17 protesting detention without charge. Around 2,000 are now taking part in the strike, rights groups say.

Abbas warned Tuesday that the death of any one of the hundreds of prisoners on hunger strike in Israel would be a "disaster" and could trigger a backlash that might slip out of control.

"It is very dangerous," Abbas said.

The EU has urged Israel to provide proper medical care to hunger-strikers, and the International Committee of the Red Cross called on Israel on Tuesday to transfer six prisoners who have forsworn food for around two months to hospital.

All six are in prison under Israel's long-standing policy of detaining people without charge. They have been refusing food for between 49 and 72 days.

On Tuesday Israel transferred Bilal Diab, who has refused food for 72 days, from hospital to a prison clinic, Physicians for Human Rights - Israel said Wednesday.

"The (Israeli Prison Service) clinic is not adequate both ethically and professionally to treat hunger strikers. For a life saving resolution to have a chance, hunger strikers must be hospitalized," PHR-I said in a statement.