Tel Aviv - Israel on Saturday marks the 1,000 days of captivity of its soldier Gilad Shalit, held in Gaza by the armed wing of the radical Islamist Hamas movement.

Shalit's family is to commemorate the date with a mass rally in Jerusalem on Saturday evening. After that they plan to abandon the protest camp they have set up outside the official residence of outgoing Prime Minister Ehud Olmert.

On Friday Israel's biggest-selling Yediot Ahronot and Ma'ariv dailies carried large banner headlines Friday, reading "1,000 days in captivity."

The Olmert government attempted a last-ditch bid to secure Shalit's release during its final days in office, through intensive indirect negotations, mediated by Egypt, with Hamas.

But the negotiations collapsed this week over Hamas' insistence that Israel free hardcore militants involved in some of Israel's worst suicide attacks. Olmert government's refused to do so.

An unnamed Egyptian official told the pan-Arab al-Hayat newspaper Friday that a deal could still be reached before the end of Olmert's term, but local observers gave this little chance, unless Hamas unexpectedly back down from its demand.

Olmert said earlier this week he has "red lines" he will not cross.

The breakdown of the negotiations has further heightened the tensions between Israel and Hamas. While Hamas has threatened to kidnap more soldiers, Israel warned it will toughen the conditions of Hamas and Islamic Jihad militants held in its jail.

Those measures would include limiting Red Cross and family visits and stripping prisoners of their television sets and radios. Israel has established a committee studying the legal aspects of such moves.

After the collapse of the talks, Israel on Thursday arrested 10 senior Hamas political leaders in the West Bank, including four legislators.

It has also threatened to reimpose limits on goods going into Gaza to the bare minimum needed to avoid a humanitarian crisis. The amount of humanitarian aid entering Gaza had increased during and after Israel's recent 22-day Gaza offensive.

The Israeli B'Tselem human rights group issued a statement saying Hamas was holding Shalit hostage in violation of international law.

Shalit was captured by Hamas in a cross-border raid from Gaza on June 25, 2006. Hamas and two other factions dug a tunnel under the border into Israel and attacked a military outpost, killing two soldiers and kidnapping Shalit.

Shalit was then smuggled back into the Gaza Strip to be used as a bargaining chip against Palestinian militants held in Israeli jails.

"The circumstances of his capture and the behaviour of his captors clearly indicate that he is a hostage," B'Tselem said.

"International humanitarian law absolutely prohibits taking and holding a person by force in order to compel the enemy to meet certain demands, while threatening to harm or kill the person if the demands are not met," it said, adding hostage-taking was considered a "war crime" for which all involved in the it bore individual criminal liability.

It noted he was being held in an unknown location isolated from the outside world, without being allowed visits by representatives of the International Committee of the Red Cross (ICHR), which it called "a blatant violation of international law" that cast "a heavy shadow over the claims that Shalit's condition is good."

The Gaza-based Palestinian Centre for Human Rights in return accused Israel wit using its jailed Palestinian militants as "bargaining chips" by threatening to toughen their prison conditions.

Using the prisoners "to exert pressure" on Hamas is a "violation of their inherent human dignity" and would constitute "collective punishment" illegal under international law, said a statement issued by the centre late Thursday.

The statement noted that families in the Gaza Strip have been unable to visit relatives detained in Israel for the last 33 months of closure, imposed since Shalit's capture and in response to rocket attacks.

Families of prisoners in the West Bank are only permitted sporadic, infrequent visitation rights, it said. Israel currently holds some 8,000 Palestinians "security" prisoners, jailed for a variety of offenses ranging from membership of outlawed armed wings of militant factions, weapons-smuggling and involvement in shooting and bombing attacks against Israelis. (dpa)