The family of a captured Israeli soldier set out on Sunday on a 12-day march to Jerusalem to press Israeli leaders to make a deal with his Hamas captors to free him.

Sgt Gilad Schalit was taken captive four years ago during a cross-border raid by militants from the Gaza Strip. His parents say they will camp outside Prime Minister Benjamin Netanyahu's official residence until their 23-year-old son is released.

"Today we say, 'We won't wait any longer, we won't wait any longer in our home,'" Schalit's father, Noam Schalit, said before starting the march. Israel's leaders, he added, "have to put an end to this sad saga."

Thousands, including supermodel Bar Refaeli and dozens of local celebrities, are expected to join the march.

Israel has agreed to release many of the 1,000 Palestinian prisoners that Hamas wants freed but has balked at releasing some of those who were convicted of involvement in deadly attacks on Israelis.

Schalit's capture helped spark Israel's blockade of the Gaza Strip. Israel had hoped the embargo would force Hamas, which rules Gaza, to release the soldier.

The blockade has been eased in recent weeks after a deadly Israeli raid on a blockade-busting flotilla drew an international outcry over the plight of 1.5 million Gazans affected by the embargo.

Schalit's parents say the Israeli government has abandoned their son and lost important leverage over Hamas by easing the embargo without assuring his release.

Netanyahu told his Cabinet on Sunday that the government was working to free the serviceman and urged the international community "to stand by the state of Israel in its unequivocal and just demand that our captive soldier be returned immediately."

Little is known about Schalit's condition. His captors have barred any access to him and released only a brief videotaped statement last year to prove he was still alive.

Netanyahu has been careful to avoid any public conflict with Schalit's parents. But Israel has a long history of paying a disproportionate price for its captive soldiers.