Said Siyam was one of the top Hamas leaders in the Gaza Strip
One of the top Hamas leaders in Gaza has been killed in an air strike, Hamas and Israeli officials have said.
Said Siyam, the Hamas interior minister, was killed in an air raid on his brother's home near Gaza City.
Earlier, Israeli troops and tanks moved closer into the heart of Gaza City, engaging in fierce gun battles with fighters from Hamas.
The UN's relief agency, Unrwa, said part of its HQ in Gaza caught fire after being hit by Israeli shells.
As interior minister, Mr Siyam controlled thousands of Hamas security troops in Gaza and was said to be widely feared.
His son and brother were also killed in the strike, along with two other Hamas officials - the interior ministry's security director Saleh Abu Sharkh and the local leader of the Hamas militia, Mahmoud Abu Watfah.
PROFILE: SAID SIYAM
Born: 1959, Shati refugee camp
Six children - two boys, four girls
Member of Hamas Political Bureau
Elected to Palestinian Legislative Council in 2006; top Hamas MP
Became Hamas interior minister in 2007, after serving one year as Palestinian interior minster
Said to have become member of Hamas "collective leadership" in Gaza after 2004 killings of Sheikh Yassin and Abdel-Aziz Rantissi
Created Hamas Executive Force, a paramilitary which played key role in take-over of Gaza in June 2007
A total of 1,083 people in Gaza have now been killed since the Israeli operation began, Gaza's Ministry of Health said on Thursday - 70 higher than the previous day's figure. Nearly a third of the dead are children, Gaza medics said.
Thirteen Israelis - including three civilians - have died. Two-hundred-and-thirty-three soldiers have been wounded, an Israeli army spokesman said.
As the clashes continued in Gaza, about 25 rockets were fired from the territory into southern Israel, Israeli police said.
Eight people were injured in Beersheba from the rocket fire, Israeli medical officials said.
As Gaza saw one of the fiercest days of fighting since the conflict began on 27 December, international condemnation of the Israeli operation grew.
In the midst of a Middle East tour to rally support for an end to the fighting, Mr Ban repeated previous calls for an immediate ceasefire.
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