BETHLEHEM (Ma'an) -- Prison doctors have told Thaer Halahla that he could die at any moment after 72 days on hunger strike, his lawyer Mona Neddaf said Thursday.

Neddaf visited Halahla, 33, in Ramle prison clinic on Thursday, the prisoner rights group Addameer said in a statement.

He is vomiting blood, bleeding from his gums and lips and has extremely low blood pressure, she said. His temperature is fluctuating at dangerous levels and the prison doctor said he also has an infection.

He has refused food since Feb. 29 and now weighs 55 kilograms.

Israel has ignored calls by the European Union and the International Committee of the Red Cross to transfer long-term hunger-strikers to hospitals and to allow them family visits.

Prison authorities on Wednesday canceled a visit from his family, scheduled for Thursday, but the detainee remains mentally strong, his lawyer said.

In Ramallah, meanwhile, President Mahmoud Abbas met 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 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.

On Tuesday, Halahla said he had no plans to back down from the strike despite suffering severe medical complications, in a letter published by the Muhjat al-Quds prisoner rights group.

"We did not go into the battle because we love to be hungry or in pain, but for our dignity and the dignity of our nation," he wrote.

He also thanked supporters who showed up for his latest court hearing.

Neddaf visited three other prisoners on long-term hunger strike, including Bilal Diab who has also been on hunger strike for 72 days.

Prison authorities have told the hunger strikers they must stand for a "daily count" or they will not be allowed to see their lawyers, she said.

Halahla and Diab are being held in administrative detention and have not been tried or charged with any offense. On Monday, Israel's Supreme Court on Monday rejected appeals to release them.

On Wednesday, UN chief Ban Ki-moon called on Israel to either charge or free Palestinian detainees immediately.

"(Ban) reiterates that those detained must be charged and face trial with judicial guarantees, or released without delay," a statement issued through his spokesman Martin Nesirky said.

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.

Islamic Jihad leader Mohammad Al-Hindi said Sunday that the death of any hunger-striking prisoner will start the third intifada, referencing the popular uprisings against Israeli occupation.

The Jihad official said the "battle of the empty stomachs" -- in which more than 2,000 jailed Palestinians are refusing food -- had overcome factional divisions.

"This battle will be the gateway for Palestinian unity," he told supporters of the hunger-strikers at a solidarity tent in central Gaza City.