Thousands of Palestinians have taken to the streets of Gaza to mourn a Hamas leader and his family killed in an Israeli raid.

Nizar Rayyan was assassinated on Thursday along with 14 members of his family.

His funeral was held in the Jabaliya refugee camp on Friday as Israeli military aircraft continued their sorties overhead.

The toll over the first seven days of Israel's aerial bombardment on Gaza has now reached 428, with the latest casualties including three children who had been playing outside.

Israel continued to bomb ground near its boundary clearing it of landmines, increasing speculation that a ground offensive is imminent. Israel says its war is against Hamas in response to rockets fired into the south of the country.

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Most residents remain trapped within Gaza, suffering severe food and power shortages after two years of an Israel-imposed blockade.

Tanks, armoured vehicles and troops have been massed along the boundary for the best part of a week, but so far there is no sign as to when they will roll in.

Gaza medical sources say the number of Palestinians wounded, many of them women and children, is now in excess of 2,100.

Palestinian factions launched seven rockets on Friday, some landing as far as the port city of Ashdod, more than 30km from Gaza. An Israeli woman was injured in the rocket fire, the Israeli army said.

Jacky Rowland, Al Jazeera's correspondent reporting from southern Israel, said: "This is two days of very heavy bombing, particularly in the north now, which has made people wonder whether this could be a foretaste of a ground offensive.

"It could be that Israeli forces are trying to clear any obstacles, notably landmines that could potentially lie in the path of advancing tanks if and when the ground offensive begins.

"But the real question now is not if, but when. Many people in Israel are wondering 'what are we waiting for'."

Meanwhile Condoleezza Rice, the US secretary of state, said on Friday that the US was working towards a "durable and sustainable ceasefire" but that any such ceasefire would not allow a “reestablishment of the status quo ante" where Hamas could continue to launch rockets.

Rice also heavily criticised Hamas for rejecting a truce and accused the group of holding the inhabitants of Gaza hostage, saying Hamas "has made it very difficult for the people of Gaza to have a reasonable life".

Talking to Al Jazeera, Osama Hamdan, a senior Hamas official in Beirut, said that the party to be blamed for the present situation is Israel, not Hamas. 

"It's clear now that Israelis are blocking all the political solutions. The main question is supposed to be what will be the right end for this? And the clear answer is ending the occupation."

Hazem Abu Shanab, a Fatah leader, also stressed the need for a political solution.

"We don't want to die under the Israeli aggression and occupation. We want the international community and the Americans to tell the Israelis to stop the bloodshed over our people," he said.

"We want to be free and we want to be just like other people."

Hamas leader killed

In the strikes on Thursday, Israeli jets pounded the border town of Rafah in the south of the territory and the Jabaliya refugee camp to the north.

Rayyan is the most senior Hamas official killed in the current Israeli offensive

Hamas officials hit back at Israel after the attack saying the assault on Gaza would fail.

"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 has committed," Ayman Taha, a Hamas official, said.

Ayman Mohyeldin, Al Jazeera's correspondent in Gaza, said the killing of Rayyan comes at a time when international organisations are saying Israel's policy of bombing the homes of Hamas leaders is against international law.

"While they may be targeting senior members of the factions and military wings, these organisations say there is no doubt that there are families there and they are in residential neighbourhoods," he said.
 
"As we have seen in this particular strike, it was a direct hit in the heart of the Jabaliya camp, the most densely populated in Gaza, home to 70,000 Palestinians."

Israel says its assault on Gaza is aimed at ending persistent Hamas rocket attacks from the enclave, but its offensive has sparked international condemnation and protests around the world.

In Jerusalem on Thursday, a coalition of left-wing parties and peace groups voiced their opposition to the raids with a protest in front of the Israeli prime minister's home. 

The protesters called for an immediate end to the assault, saying the escalation of violence was a disaster for both sides. 

Meanwhile Tayyip Erdogan, Turkey's prime minister, has called for an immediate ceasefire from both sides.

"Our call to Israel now is to halt its fire and to the other side to stop firing rockets and other attacks," he said after talks with Egypt's president in the Red Sea resort of Sharm el-Sheikh.

Desperate Gazans

With Israel continuing to pound Gaza, the situation for Gaza residents is becoming increasingly desperate.

Israeli tanks and troops have been massing at the Gaza border [AFP]

Hospitals have also reported shortages of even the most basic medicines and say they have no more capacity to deal with the growing numbers of casualties.

On Thursday, however, Tzipi Livni, the Israeli foreign minister, denied suggestions there was a humanitarian crisis in the Strip, adding "and therefore there is no need for a humanitarian truce".

Livni was speaking in Paris after talks with the Nicolas Sarkozy, the French president, whose call for a 48-hour ceasefire to allow in humanitarian aid has been rejected by Israel.

"Israel has been supplying comprehensive humanitarian aid to the Strip ... and has even been stepping this up by the day," the Israeli foreign ministry quoted Livni as saying.

Karen Abu Zayed, the commissioner for the UN Relief and Works Agency (UNRWA) in Gaza, said that in eight years of working in Gaza the need for aid had "never been so acute".

"I am appalled and saddened when I see the suffering around me," she said, adding UNRWA has made an emergency appeal for $34m to help the Gaza population.

Hasan Khalaf, Gaza's assistant deputy health minister, described the ongoing assault on Gaza as "an Israeli massacre".

"There is no comparison between what we have and what [Israel] are doing to us. The international community are standing unable to help us, and yet we know they have been helping Israel for tens of years.

"Even now they are comparing those getting scared in the south of Israel, and those buried under the rubble after having their houses bombarded."