GAZA Israel launched a ground offensive in the Gaza Strip on Saturday, sending tanks and infantry into battle with Hamas fighters who have defied eight days of deadly air strikes with salvoes of rocket fire into Israeli towns.
Israeli tanks killed seven Gazans at the onset of the night-time invasion, bringing the Palestinian death toll since December 27 to more than 450, medical officials said.
Israel said it called up tens of thousands of reservists and the military's chief spokesman estimated the operation in the Hamas-run enclave could take "many long days."
Wearing night-vision goggles on their helmets and camouflage paint on their faces, Israeli ground troops entered the Gaza Strip along with columns of tanks that pushed into the coastal territory from four points.
Heavy casualties are likely to increase international pressure on Israel to halt its biggest operation in the Gaza Strip in four decades, fighting that holds significant political risks for Israeli leaders ahead of a February 10 national election.
The plight of the 1.5 million Palestinians crammed into Gaza was growing more desperate. People have taken shelter in their homes for days and humanitarian agencies warned that water and medical supplies were running short.
The United Nations Security Council scheduled a special meeting for 2400 GMT to discuss the latest developments.
Several hours into the armored offensive, Israeli tanks moved some two kms (1.2 miles) into the northern Gaza Strip, taking up positions in an area frequently used by militants to fire rockets across the border, witnesses said.
A Palestinian petrol station along the invasion route was engulfed in flames after being hit by a tank shell.
A spokesman for Hamas's armed wing, the Izz el-Deen al-Qassam Brigades, said Israeli troops faced certain death or capture. "The Zionist enemy must know his battle in Gaza is a losing one," said the spokesman, Abu Ubaida.
At least a quarter of the 453 Palestinians killed in the current conflict have been civilians, a U.N. agency said. Another 2,050 Palestinians have been wounded. A leading Palestinian rights group put the number at 40 percent.
Four Israelis have been killed by rockets that continue to pound southern Israel, where residents have been told to stay home and take cover in rooms made of reinforced concrete.
Israeli Defense Minister Ehud Barak said the aim of the ground push was to "protect the home front" from rocket attacks. He stopped short in a televised address of making any threat to try to topple the Hamas government in the enclave.
"It won't be easy. It won't be short," said Barak, leader of the center-left Labour party, and a candidate for prime minister in an election that opinion polls predict will return right-winger Benjamin Netanyahu to power.
Large numbers of forces were involved in the sweep, including infantry, tanks, engineers, artillery and intelligence, the military said in a statement.
"The objective is to destroy the Hamas terror infrastructure in the area of operations," Major Avital Leibovich said. Israeli military affairs commentators said the offensive was also aimed at boosting Israel's deterrence power in the region.
Israeli troops face Hamas militants whom the United States and Israel say have received arms and training from Iran. Hamas is believed to have about 25,000 fighters and has placed landmines and other traps in anticipation of an invasion.
An Egyptian-brokered six-month truce expired on December 19 but it had been strained by Hamas rocket strikes and Israeli military operations against the group.
The United States said before the ground offensive started that it was working for a durable truce but insisted Hamas stop firing rockets first. The White House said President George W. Bush was briefed on the Israeli military action.
A spokesman for Palestinian President Mahmoud Abbas condemned the offensive as "a vicious aggression."
Former British Prime Minister Tony Blair, representing major powers sponsoring Middle East peace talks, planned to begin shuttling on Sunday between Israeli leaders and Palestinian leaders -- Hamas's rivals -- in the occupied West Bank.
But divisions within the European Union over the Israeli operation could buy Israeli more time. European Union president, the Czech Republic, said the ground assault was "defensive, not offensive" action, but it also called for a ceasefire and humanitarian aid for the region.
France condemned the Israeli ground assault, as well as Hamas rocket fire. On Monday, French President Nicolas Sarkozy is scheduled to go to Jerusalem. Israel had rejected Paris's calls for a 48-hour ceasefire.
Diplomats said the Europeans were drafting a new proposal for a truce. Political sources said some Israeli leaders favor a formal ceasefire backed by the U.N. and major powers. Other decision-makers in Israel say it would only tie their hands should rocket fire continue.
Before the advance, an air strike killed 11 Palestinian worshippers, including children, and wounded dozens at a mosque in northern Gaza, Hamas officials and medics said. Israel says Hamas has used mosques as command posts and fire bases.
One strike killed Abu Zakaria al-Jamal, a senior commander of Hamas's armed wing, Hamas said.
Israel's attacks brought a wave of international protests and thousands of demonstrators marched in solidarity with the Palestinians in European cities on Saturday.
Israel occupied Gaza in the 1967 Middle East War and after Palestinian uprisings formally ended its military rule in 2005, although it still controls the borders.
International peace efforts aimed at creating an independent Palestinian state foundered after Hamas won elections in 2006 and drove Fatah forces loyal to Palestinian President Mahmoud Abbas from Gaza a year-and-a-half later.
(Writing by Jeffrey Heller and Adam Entous; Additional reporting by Dan Williams; Editing by Sami Aboudi)