Israel on Friday denied accusations from rights groups that it had deployed the incendiary weapon white phosphorus in its war against Hamas militants in the densely populated Gaza Strip, after the Islamists' deadly attack at the weekend.

"We deny those allegations, we have not made use of white phosphorus, not in Gaza and not in Lebanon," an Israeli military spokesman said.

Israel has been pounding Hamas targets in the Gaza Strip in recent days, after the Palestinian militants stormed across its border at the weekend, killing more than 1,200 people.

A Reuters journalist was killed Friday and six others from AFP, Reuters and Al Jazeera were wounded while working in southern Lebanon, the three news organisations said.

A group of journalists from different media outlets was near the village of Alma al-Shaab, close to the border with Israel, when they were caught up in cross-border shelling, one of the two wounded AFP correspondents said.

A Lebanese security source had told AFP that initial Israeli shelling followed an infiltration attempt by a Palestinian faction from the Lebanese side of the border.

The massive Hamas attack on Israel cannot justify the "limitless destruction" of the Gaza Strip, the Red Cross said Friday, as it called for pauses in the fighting.

Its statement came as Israel's army on Friday warned residents in north Gaza to flee south ahead of an expected ground offensive.

Israel's siege of Gaza is in response to the weekend attack by Hamas, whose gunmen launched the deadliest ever attack on Israel.

"Nothing can justify the horrific attacks Israel suffered last weekend," said a statement from the International Committee of the Red Cross.

Tensions ran high in Jerusalem Old City on the Muslim day of prayer and rest Friday, as Israel's nearly week-old war against Palestinian militant group Hamas raged in and around Gaza.

The usually bustling alleyways of the Muslim quarter were nearly deserted, except for young Palestinians unsuccessfully attempting to break through an Israeli checkpoint barring them from the Al-Aqsa mosque compound, a flashpoint in the city's annexed eastern sector.

At least nine Palestinians were killed by Israeli fire in the occupied West Bank on Friday during rallies in solidarity with war-battered Gaza, the Palestinian health ministry said.

AFP correspondents and a security official reported clashes in Ramallah, Nablus, Tulkarem, Hebron and other cities, nearly a week after a massive Hamas attack on southern Israel spiralled into an all-out war.

Lebanon's Iran-backed Hezbollah movement said Friday it would be "fully prepared" to join its Palestinian ally Hamas in the war against Israel when the time is right.

Hezbollah deputy chief Naim Qassem spoke as Hamas and Israel traded heavy fire for a seventh day, after hundreds of Hamas gunmen stormed across the border from Gaza into Israel on Saturday and killed more than 1,300 people, most of them civilians.

An Israeli embassy worker in China's capital was attacked with a knife by another foreign national and hospitalised on Friday, with the suspect later arrested, officials said.

Video geolocated by AFP shows the man was stabbed with a knife on a street in the Chinese capital.

"An Israeli employee of the Israeli embassy in Beijing was attacked today," Israel's foreign ministry said in a statement, adding that the attack did not take place at the embassy compound.

The level three basement carpark in northern Israel's Rambam hospital is usually what it is called -- a place for people to leave their vehicles.

But in 30 hours this week, staff transformed the cavernous space into a huge underground hospital, equipping it with 1,300 beds, complete with fittings for oxygen, medical and sanitary supplies.

Israel is in the midst of a war to "crush" Hamas, after the Palestinian Islamists stormed its southern border at the weekend, shooting dead more than 1,200 people in the streets and in their homes.

Thousands of Palestinians fled Saturday to southern Gaza seeking refuge after Israel warned them to evacuate before an expected ground offensive against Hamas in retaliation for the deadliest attack in Israel's history.

Prime Minister Benjamin Netanyahu warned that nearly a week of fierce bombardment was "just the beginning" as Israel seeks to retaliate against Hamas after their fighters killed more than 1,300 a week ago.

The World Health Organization said Friday that a mass evacuation of the northern Gaza Strip would be "disastrous" for hospital patients, with hospitals in the south already at full capacity.

Israel has given Palestinians 24 hours to leave the northern Gaza Strip ahead of an expected ground offensive in retaliation against Hamas for the deadliest attack in Israeli history.

"The Palestinian Ministry of Health has informed WHO that it is impossible to evacuate vulnerable hospital patients without endangering their lives," the UN health agency said in a statement.