Navi Pillay, the UN High Commissioner for Human Rights, has expressed concern about the well-being of Palestinian detainees in Israeli prisons, particularly Samer Issawi who has been on hunger strike for more than 200 days and is reportedly on the verge of death.
The UN human rights chief on Tuesday called for the immediate release or charge of prisoners held in "administrative detention".
Two other Palestinians - Tarek Qaadan and Jafar Azzidine - have been on hunger strike for 78 days to protest Israel's policy of administrative detention, under which suspects can be imprisoned without trial by order of a military court. The order can be renewed indefinitely for six months at a time.
All three are reportedly near death.
Pillay said: "Persons detained must be charged and face trial with judicial guarantees in accordance with international standards, or be promptly released."
Richard Falk, UN Special Rapporteur on the situation of human rights in the occupied Palestinian territories, went further and called for the immediate release of the three men - calling the conditions the men were being held under as "inhumane".
A UN statement said that Humanitarian Co-ordinator James W Rawley met in the West Bank city of Ramallah with Palestinian prisoner affairs minister Issa Qaraqe.
"They discussed the situation of four Palestinian detainees currently on hunger strike and, in particular, the critical health condition of one Palestinian detainee, Samer Issawi."
Issawi was released along with over 1,000 other prisoners in the October 2011 prisoner swap for captured Israeli soldier Gilad Shalit.
He was re-arrested in July 2012 under disputed circumstances by the Israeli army near Hizma in Jerusalem and began his hunger strike soon after.
Issawi wants to be formally charged and given a fair trial or set free - until then, he says he will continue his hunger strike.
'Out of control'
Palestinian prisoner support group Addameer says six prisoners held by Israel are currently on hunger strike.
The longest-serving are Issawi and Ayman Sharawneh who have been fasting for months to demand their release from imprisonment without trial.
Palestinian President Mahmoud Abbas on Tuesday called on the international community to intervene urgently in support of Palestinian prisoners on hunger strikes.
"Things may get out of control if the lives of the hunger strikers are not saved," Abbas said on Palestinian television.
"We ask the international community to respond effectively to ease the situation, otherwise it will be impossible to control and it will deteriorate across the Palestinian territories."
Abbas singled out four detainees in need of special attention - Samer Issawi, Jafar Azzidine, Ayman Sharawneh and Tareq Qaadan.
"These prisoners are on hunger strike in response to the policy of administrative detention and ill-treatment by the occupying authorities," he added in reference to Israel.
Despite the recent statement by Abbas, the overall silence of the Palestinian Authority towards the plight of the hunger strikers and its efforts to silence West Bank protests rallying for the prisoners has frustrated many.
Last year, between 1,600 and 2,000 Palestinian prisoners held by Israel took part in a collective hunger strike which ended with an agreement with prison administrators on May 14.
One of their main demands was the release of administrative detainees.