Gaza Protesters Form Human Chain
Thousands of Palestinians have formed a "human chain" in Gaza in protest at Israel's blockade of the territory.
Organisers had hoped up to 50,000 people would make a 40km (25-mile) chain from Rafah to Beit Hanoun, but turnout was below expectation.
Earlier, Israel's military strengthened its positions along the border and warned it would hold Hamas responsible if the demonstration became violent.
Israel tightened the blockade when Hamas seized control of Gaza in June.
"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," said a joint statement released by Israeli Foreign Minister Tzipi Livni and Defence Minister Ehud Barak.
"Israel will work to avoid a deterioration of the situation but declares unequivocally that Hamas must assume full responsibility if that happens," said the statement.
Last month, the barrier separating Gaza from Egypt was demolished by militants, allowing hundreds of thousands of people to cross the border and obtain much-needed supplies.
Thousands of women and children from all around the Gaza Strip travelled to the main north-south road for Monday's peaceful demonstration.
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" and "The world has condemned Gaza to death."
The protest's organisers, the pro-Hamas Popular Anti-Siege Committee, had planned to place a person every metre along the 40km-long road from the Rafah crossing on the southern border to the Erez crossing near the northern town of Beit Hanoun, but reports say only around 5,000 took part.
Jamal Khudari, the head of the committee, had promised the demonstration would not risk a violent response from Israeli or Egyptian forces by going too close to either of the country's borders.
As it began to break up in the early afternoon, some 50 schoolchildren reportedly ran towards the Erez crossing and started throwing stones.
Israeli soldiers at the checkpoint are said to have fired into the air to scare the children away and no casualties have been reported.
Earlier, an Israeli military spokesman, Col Zeev Sharoni, insisted the army would "do everything necessary to prevent people from crossing into Israeli territory."
BBC Arab affairs analyst Magdi Abdelhadi says the Palestinians in Gaza appear to have realised that mass action is their best chance of getting the attention of the world and generating more pressure on Israel to ease the blockade.
With Israel refusing, and Hamas and Fatah locked in a power struggle, they want to send a clear message to the outside world that ordinary civilians are paying the price, he says.
On Sunday, two Hamas fighters were killed in Israeli airstrikes near the border in Khan Younis, while another died in northern Gaza, the group said. Israeli forces also detained 40 Palestinians and said they had discovered five smuggling tunnels along the territory's frontier.
Israeli authorities fear a repetition of scenes from last month, when the fence separating Gaza from Egypt was demolished by Palestinian militants in several places near the Rafah crossing point.
Hamas officials have since raised the possibility of similar breaches along the border with Israel.
Israel's blockade of Gaza was imposed after Hamas routed Fatah forces loyal to President Mahmoud Abbas last June and seized control of the Gaza Strip.
Israel said the siege, which has prevented the flow of everything but essential humanitarian supplies, was in response to cross-border rocket attacks by militants in Gaza.
But Palestinians and several international agencies have said the sanctions amount to collective punishment of Gaza's 1.5 million civilians.