By Nidal al-Mughrabi
GAZA (Reuters) - Israel killed a senior Hamas leader in an air attack on his home on Thursday, striking its first deadly blow against the top ranks of the Islamist group in a Gaza offensive that has claimed more than 400 Palestinian lives.
Nizar Rayyan, a cleric widely regarded as one of Hamas's most hardline political leaders, had called for renewed suicide bombings inside Israel. Medical officials, confirming his death, said another nine people, including members of Rayyan's family, were killed in the bombing in Jabalya refugee camp.
Many Hamas leaders are in hiding, anticipating assassination attempts by Israel, whose military confirmed the air strike. Hamas Radio said Rayyan rejected Hamas advice to leave his house.
Rayyan, 49, an influential preacher at what is known in Jabalya as the "mosque of martyrs" mentored suicide bombers and with an ammunition belt strapped to his stocky frame, would sometimes patrol with Hamas fighters.
"The blood of Sheikh Nizar Rayyan and the blood of other martyrs will never be wasted and the enemy will pay a heavy price for the crimes it committed," said Hamas official Ayman Taha.
Hours before the killing, Prime Minister Ehud Olmert said Israel was fighting Hamas with an "iron fist," his words backed by a series of air strikes in the Gaza Strip but challenged by rockets that have killed four people in southern Israel.
Israeli forces remained poised on the Gaza frontier in preparation for a possible ground invasion as international calls for an immediate cease-fire mounted.
Shortly after Olmert spoke to mayors in southern Israel, footage of a multi-storey building damaged in an attack and a rubble-strewn street filled Israeli television screens.
This time, the scene was the not the battered Gaza Strip, rather a tree-lined street in Ashdod, a major Israeli port city, where a Hamas rocket had torn into the eighth floor of a residential building.
No one was hurt but several residents were treated for shock, officials said. Some 20 rockets hit elsewhere in southern Israel, causing no casualties.
On the sixth day of hostilities, Israeli aircraft and naval forces attacked about 20 Hamas targets in the Gaza Strip, including a government complex, the Israeli military said.
Palestinian medical officials said three civilians were killed in those air strikes and 100 people wounded.
"I very much hope we will succeed in achieving our goals quickly," Olmert said, repeating Israel's declared aim of ending rocket attacks in the Gaza Strip and giving no precise timeframe for the offensive that began on Saturday.
Diplomats said the deadliest conflict in the Gaza Strip in four decades could get even bloodier after days of air strikes that have killed at least 410 Palestinians, about a quarter of whom, U.N. figures showed, were civilians, and wounded more than 1,700.
Foreign pressure grew on both sides to hold their fire but Israel brushed aside as "unrealistic" a French proposal for a 48-hour truce that would allow in more humanitarian aid for Gaza's 1.5 million residents.
In New York, the U.N. Security Council held an emergency session but adjourned without a vote after Arab countries pushed for a demand for an immediate cease-fire. Western delegates described the Arab-drafted resolution as unbalanced and said negotiations would continue to reach an agreed text.
The Czech prime minister, who holds the European Union presidency, said he was planning to organise a diplomatic mission on behalf of the bloc to the Middle East to address the conflict there.
France said it would host Israeli Foreign Minister Tzipi Livni on Thursday and an Israeli official said French President Nicolas Sarkozy planned to visit Jerusalem on Monday.
The Gaza operation, launched after a six-month cease-fire expired on December 19 and Hamas intensified rocket strikes, could affect the outcome of Israel's February 10 national election.
A poll in the Haaretz daily showed a majority of Israelis, 52 percent, favoured pursuing the attacks in Gaza, with just 20 percent backing calls for a cease-fire, and 19 percent favouring the launch of a ground offensive into Gaza.
Hamas leader Ismail Haniyeh said Israeli attacks must stop before any truce proposals could be considered. Israel must also lift its economic blockade of Gaza and open border crossings.
Olmert told his security cabinet on Wednesday that if a diplomatic solution could be found that ensured better security for southern Israel, the government would consider it.
Food supplies in Gaza were running low and there were power cuts. Hospitals struggled to cope with the high number of casualties from the offensive.
Seventy trucks carrying humanitarian supplies, including aid from Saudi Arabis, crossed into the Gaza Strip from Israel on Thursday, Palestinian officials said.
(Additional reporting by Adam Entous and Jeffrey Heller in Jerusalem, Patrick Worsnip at the United Nations and James Mackenzie in Paris; Writing by Jeffrey Heller; Editing by Keith Weir)