Thousands of Palestinians formed a human chain today in a peaceful protest against the international blockade of the Gaza Strip.

Men, women and children holding both Palestinian and Hamas flags turned out for a protest which organisers linked to the ruling Hamas movement claimed had attracted some 50,000 people.

The organisers said that the human chain - designed to link a 25-mile stretch of the main road traversing the centre of the coastal strip between the towns of Rafah and Beit Hanoun - was designed to show up the plight of Gaza residents to the international community.

Schools were closed for the day, and thousands of pupils were taken in buses to participate. Many could be seen with banners stating: "The Siege of Gaza Will Only Strengthen Us, "The World Has Condemned Gaza to Death" and "Save Gaza".

The international community has largely boycotted Gaza since Hamas, which refuses to renounce terrorism or recognise Israel's right to exist, deposed the secular Fatah movement in a military coup to take control. Fatah, which is led by the Palestinian President Mahmoud Abbas, still controls the West Bank.

"This is a peaceful and civilised act to let the people express their rejection of the siege and of collective punishment," Jamal al-Khudari, leader of the Popular Committee Against the Siege, the pro-Hamas organisers, said. "We are raising a cry to the world for it to act."

Ismail al-Ashqar, a Hamas MP, warned that, if the international community ignored the demonstration, "there will be a hurricane that will flood the whole region".

The Israeli military strengthened its positions along the border and warned that Hamas would be held responsible if the protests turned violent. Israel has sealed the territory to all but vital humanitarian supplies in a bid to put pressure on Hamas to halt rocket and mortar attacks on the southern Israeli town of Sderot.

"Israel will not intervene in demonstrations inside the Gaza Strip but it will ensure the defence of its territory and prevent any violation of its sovereign borders," a joint statement issued by Tzipi Livni, the Foreign Minister, and Ehud Barak, the Defence Minister, said.

The statement accused Hamas of "orchestrating a premeditated effort to put civilians on the front line".

It added: "Israel is working to prevent an escalation, but has made it absolutely clear that if there is an escalation, the responsibility will be entirely on Hamas’s shoulders."

The protest appeared to have passed off without significant incident this afternoon, with a small group of youths reported to have set fire to a tyre a few yards from the Israeli Erez border crossing and thrown stones.

The incident drew fire from Israeli soldiers, and two of the youths were wounded.

At the same time, the army said it had arrested "around 50" Palestinians who had approached the crossing.

Meanwhile, an explosion in the central Israeli city of Rishon Leziyon left two people seriously injured.

The military said one of the wounded men was an officer and the other a non-commissioned officer, and that the blast took place at an army firing range.

It has not yet been established whether the explosion was due to a Palestinian militant attack. The Army said it was investigating.

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