The treatment of the 23-year-old soldier, captured exactly four years ago by Hamas, is "cruel and inhuman" and matches a UN definition of torture because he is denied any outside contact, the US-based rights group said in a statement.
Hamas-affiliated militants captured tank crewman Sgt.
Gilad Schalit inside Israel in 2006 and have been holding him since then in Gaza, the coastal Palestinian territory controlled by the militant Islamic organization.
Negotiations over a deal that would see Israel win Schalit's release by freeing hundreds of Palestinian prisoners, including militants convicted of deadly attacks against civilians, have stalled.
Hamas released a video of Schalit in October 2009 to prove the soldier was alive. His current condition is unknown.
The statement from Human Rights Watch notes Israeli violations of Palestinian rights, including limitations on visitation rights for some Palestinian prisoners in Israeli jails, but says violations by one side "do not justify violations by the other." Schalit has dual French-Israeli citizenship and on Friday French President Nicolas Sarkozy released a letter he had addressed to the abducted soldier's parents.
"Like all French people, I'm indignant that a man could be deprived of freedom in such a way," Sarkozy wrote.
"Such treatment, which totally lacks humanity, ignores universally recognized principles when it comes to prisoners, firstly the visiting rights of the International Committee of the Red Cross." Schalit's father Noam met with the French ambassador to Israel Friday afternoon. Noam Schalit told reporters that Sarkozy had promised to continue his efforts to release his son. "They have means that Israel maybe does not have," he said.
Also Friday, Palestinians officials in Gaza said they retrieved the bodies of two Palestinians killed after Israel bombed a weapons smuggling tunnel overnight on the Gaza-Egypt border.
The Israeli military said the tunnel was targeted because Palestinians fired 12 rockets and mortars into Israel Thursday. Nobody was hurt in the barrage the Israeli military said because the shells exploded in open fields.
Schalit's parents have begun a new effort to rally public support for a deal to release the soldier. They have urged the release of Palestinian prisoners and criticized Israel's government this week for a recent decision to ease a blockade on the Gaza Strip, saying the blockade was an important bargaining chip for their son's release.
Israel arrested dozens of Hamas officials and legislators after Schalit's capture, which came just months after the Islamic group won Palestinian parliamentary elections, and carried out another wave of arrests the following year.
Many of the Hamas officials have since been released but several dozen remain in detention, according to the Israeli rights group B'Tselem.
Four of the Hamas politicians released from prison are expected to be forced from their homes in Israeli-controlled east Jerusalem after the Israeli government stripped them of their residency rights, saying the men are senior members of a terror organization.
The men could be forcibly evicted by police as early as Friday.
Jerusalem police would not comment on a planned time for an eviction.
Palestinian President Mahmoud Abbas, a Hamas rival whose government in the West Bank has itself cracked down on members of the Islamic group, called the Israeli move a "dangerous precedent" and said Israel was creating "the biggest obstacles yet on the path to peace."
