Gilad Shalit, 23, has been held in Gaza by Hamas militants who are demanding the release of hundreds of Palestinian prisoners in exchange for his release.

Thousands are expected to rally outside the military headquarters in Tel Aviv calling for his release.

His parents plan to stage an 11-day cross-country march starting on Sunday.

Frustrated with failed attempts to free their son, Sgt Shalit's parents are beginning the long walk from their home in northern Israel to the prime minister's home in Jerusalem.

The say they will remain camped there until they see their son again.

The campaign has widespread support among Israel's public and in the country's media.

Hopes renewed

Sgt Shalit was captured in a raid into Israel by militants in 2006 exactly four years ago.

He is being held in Gaza, and has had little contact since then with the outside world.

Apart from one audio recording and a video tape, which appeared to show him in relatively good health, there has been little contact with the soldier.

Militants from Hamas, the Palestinian organisation which controls Gaza, have also refused the International Red Cross access to Gilad Shalit - a stance that has been widely criticised in Israel and beyond.

Talks to free the soldier in return for a number of Palestinian prisoners broke down last year.

One of the main reasons for Israel's long blockade of Gaza was the continued detention of Sgt Shalit, the BBC's Wyre Davies reports from Jerusalem.

Now that Israel has eased - if not completely lifted - that embargo, it hopes and expects that Sgt Shalit will be released, our correspondent adds.