Israel has sealed its borders with the Hamas-ruled Gaza Strip after a surge in cross-border attacks this week. As Robert Berger reports from VOA's Jerusalem bureau, the move is raising fears of a humanitarian crisis in the impoverished territory.

A Palestinian demonstrator runs to avoid a stun grenade thrown by Israeli soldiers during a demonstration against Israel's separation barrier in the West Bank near Ramallah, 18 Jan. 2008

Israel has closed all border crossings into Gaza, in response to an escalation in Palestinian rocket attacks. The Islamic militant group Hamas, which rules Gaza, has fired more than 100 rockets at Israel since Tuesday, when Israeli forces killed 19 Palestinians, most of them Hamas gunmen.

The rocket attacks have terrorized the Israeli town of Sderot and farming communities on the Gaza border. Israeli spokesman Arieh Mekel says that under these circumstances, it cannot be business as usual with Gaza.

"We are determined to continue and do whatever it takes until these daily attacks against our citizens will stop," he said.

The closure is a further blow to besieged Gaza, which is already facing shortages of food, raw materials, fuel and electricity. Israel has tightened sanctions since June, when Hamas seized control of Gaza and defeated the Fatah forces of western-backed Palestinian President Mahmoud Abbas.

Dr. Mona al-Farra of the Palestinian Red Crescent in Gaza says the situation is going from bad to worse.

"I am warning of a large humanitarian crisis in Gaza for [the] Palestinian people, for women [and] children," she said.

Israel hopes that the sanctions, along with military pressure, will prompt Palestinians in Gaza to pressure Hamas to halt the rocket attacks. But Hamas and other militant groups are defiant. They say Israeli "collective punishment" will not stop the rockets.

The government of President Abbas in the West Bank also condemned the border closures. Palestinian officials warned that Israel is harming new peace talks, which resumed last month after a seven-year break.