Captured Israeli soldier Gilad Shalit is seen in this file photo of a video grab released October 2, 2009 by Israeli television, (Reuters).
Israeli, Palestinian and international human rights groups issued a joint statement on Friday demanding that Gaza militants end "inhumane" treatment of an Israeli soldier they hold captive.
The declaration, signed by Israeli group B'Tselem, the Gaza-based Palestinian Centre for Human Rights, Amnesty International, Human Rights Watch and eight others, comes as Israel marks the fifth anniversary of the capture of Gilad Shalit by three groups, including the Islamist Hamas.
"Those holding him have refused to allow him to communicate with his family, nor have they provided information on his well-being and the conditions in which he is being held," the statement said in English, Arabic and Hebrew. "This conduct is inhumane and a violation of international humanitarian law."
"Hamas authorities in Gaza must immediately end the cruel and inhuman treatment of Gilad Shalit," it added. "Until he is released, they must enable him to communicate with his family and should grant him access to the International Committee of the Red Cross."
In a message accompanying the statement, B'Tselem pointed out that its wording represented a consensus between groups with disparate views on the Shalit case.
"The organisations take a variety of positions on the issue," it wrote. "Some call for the immediate release of Shalit, while others support a prisoner swap."
"Some of the organisations have not made any statements until today. It is therefore particularly significant that the organisations have united around a joint message."
An Israeli spokesman for the International Committee of the Red Cross, Ran Goldstein, told Israeli public radio that the organisation had been in contact with Hamas since the soldier was captured.
"Our main option is covert dialogue and that's what we've been doing for five years in the case of Gilad Shalit, whether in Gaza or elsewhere, meeting senior Hamas officials with the aim of getting access to Gilad Shalit and also in an attempt to persuade them to let him contact his family," he said.
Israeli prime Minister Benjamin Netanyahu said on Thursday evening that in response to Hamas's continuing refusal to allow Red Cross visits to Shalit he had instructed the Israel Prisons Service to curtail privileges granted to Palestinian militant inmates.
"I'm not going to detail the measures, but I can tell you the party's over," Netanyahu said in a speech at an international conference in Jerusalem.
"I would like to give one example: I have stopped the absurd procedure whereby terrorists in Israeli prisons for murdering innocents can sign up for academic studies. There will be no more masters degrees in murder or doctors of terrorism," he said.
Shalit was 19 when he was captured in southern Israel on June 25, 2006, by militants who staged a cross-border raid from the Gaza Strip. He has been held ever since at a secret location there.