Several dozen Palestinians on Wednesday blocked staff from entering UN offices in Ramallah to demand that UN chief Ban Ki-moon take action over hunger striking prisoners.
The demonstrators, who blocked UN employees from entering the building, waved banners reading: "UNjust" and "UNfair."
More than a third of the 4,700 Palestinian prisoners being held by Israel are currently observing an open-ended hunger strike.
Two of them are marking their 71st day without eating in protest at their being held without charge under a procedure known as administrative detention which allows Israel to hold suspects indefinitely for renewable periods of up to six months.
The vast majority began refusing food on 17 April to demand improved conditions, including increased access to lawyers and family visits, an end to solitary confinement and administrative detention.
Until now, Israel has rejected all appeals lodged by the hunger strikers, has refused them family visits and only briefly transferred one of them to a civilian hospital, sparking mounting protests from human rights groups as well as the UN.
"We are disappointed with your silence since the start of this protest in December 2011," protest organizers said in an open letter to Ban, referring to the month when a prisoner called Khader Adnan began a 66-day hunger strike which put the international spotlight on the issue of administrative detention.
"This contrasts starkly with your constant strong statements of support for the imprisoned Israeli soldier Gilad Shalit," they said, referring to a soldier who was held captive by Gaza's Hamas rulers for more than five years and released in October last year.
"We demand that you take a decisive stance against the Israeli violation of the prisoners' rights," it said, demanding that the UN "encourage its member states to oppose these flagrant violations of their human rights."
The office of Robert Serry, the UN's Middle East envoy, had no immediate comment on the protest.