Hamas fights back after Israeli troops slice the Gaza Strip in half

ISRAELI troops and tanks divided the Gaza Strip and surrounded its main city yesterday in an offensive against Hamas that has killed about 500 Palestinians, many of them civilians.

The Middle East's most powerful army pounded Gaza City and the Strip with tank shells as well as machine-gun fire and air strikes, as Islamic Hamas fighters fought back with mortars and rocket attacks against southern Israel.

Last night, the Prime Minister, Gordon Brown, called for an immediate ceasefire in the region. He added: "The Israelis must have some assurance that there are no rocket attacks coming into Israel."

Middle East peace envoy Tony Blair met the Israeli defence minister, Ehud Barak, in an attempt to defuse the conflict. European Union foreign policy chiefs also pledged £3 million in emergency aid to Gaza and launched a mission to seek a ceasefire.

Benita Ferrero-Waldner, the EU's external relations commissioner, said: "It is absolutely necessary that the violence has to stop."

However, a UN Security Council resolution drafted by Libya was thought to have been vetoed by Washington, which considers Hamas a terrorist organisation.

Senior Israeli officials warned the offensive could last many days. The Israeli president, Shimon Peres, said: "We don't intend to occupy Gaza nor to crush Hamas, but to crush terror. And Hamas needs a real and serious lesson. They are now getting it."

Israel's prime minister, Ehud Olmert, insisted his country had exhausted every avenue before launching its ground assault, saying: "This is an unavoidable operation."

At least 42 Palestinians, most of them civilians, were killed yesterday as Israeli shells slammed into houses and buildings in Gaza's main shopping district, bringing the Palestinian death toll in the nine days of Operation Cast Lead to 512. The UN estimates at least a quarter were civilians.

Saturday night's invasion of the Hamas-ruled Gaza Strip followed a week of Israeli bombardments from land, sea and air – the most serious Israeli-Palestinian fighting seen in decades. One Israeli soldier was killed and 32 were wounded in the ground offensive, Israel said. Four Israelis have been killed by Hamas rocket strikes since 27 December.

Yesterday morning saw gun battles between Hamas fighters and Israeli soldiers, then later the exchanges consisted mostly of Israeli tank shells and Hamas rocket and mortar fire.

"The Zionist enemy must know his battle in Gaza is a losing one," Abu Ubaida, a spokesman for Hamas' armed wing, said.

A Red Crescent doctor said "everyone is terrified" after two children were dismembered by a blast from a tank. He said: "Civilians are being killed … shells are severing people's legs, shrapnel is going into people's bodies and into people's homes; a lot of people are being cut down."

A Palestinian paramedic working for the Oxfam-funded Union of Health Work Committees was killed in Gaza yesterday after an ambulance was hit by an Israeli shell. A second paramedic lost his foot and the ambulance driver was injured. They had been trying to help evacuate an injured person in the Beit Lahiya area.

Israel's offensive has sparked strong condemnation across the Muslim and Arab world. Thousands of people have protested in cities across the region.

Meanwhile, speaking at St Andrew's Cathedral in Glasgow yesterday, Mario Conti, the Catholic Archbishop of Glasgow, called for an end to the violence. He said: "I have been appalled at the violence first displayed against, and now by Israel – rockets met by bombs and a tank invasion. Fear stalks both sides of the Gaza border."