The Gaza Strip faces a "a full-blown humanitarian crisis", the International Committee of the Red Cross (ICRC) says.

The ICRC's head of operations for Gaza, Pierre Kraehenbuhl, told the BBC that life was becoming intolerable in Gaza after 10 days of conflict.

Clashes between Israeli forces and Palestinian gunmen continue as Israel attempts to end militant rocket fire.

Palestinian medical officials say at least 110 people have died since the ground assault began on Saturday.

Israel says it has killed 130 Hamas fighters and has denied claims that Hamas has killed 10 of its soldiers.

More than 560 Palestinians have been killed since Israel moved to end rocket attacks from Gaza 11 days ago, Palestinian medical officials say. The UN says at least 25% of those are civilians.

At least 20 Palestinians were killed on Tuesday, while three Israeli soldiers were killed by fire from one of their own tanks in northern Gaza.

Israel says its offensive stopping militants firing rockets into its territory, but at least five missiles hit southern Israel on Tuesday, with one reaching the town of Gadera, about 40km (25 miles) from the Gaza Strip.

'Intolerable situation'

"After 10 days of uninterrupted military operations in the Gaza Strip, what we're dealing with is clearly and beyond doubt in my mind a full-blown and major humanitarian crisis," the ICRC's Pierre Kraehenbuhl told the BBC.

"For the people inside Gaza, the situation has become intolerable... The reports we've had during the night is that the last night has been the most intense in terms of bombardments and military operations."

There was heavy fighting around Gaza City overnight as infantry supported by tanks and helicopters approached the outskirts of the city.

More clashes were reported on the edges of the Deir al-Balah and Bureij refugee camps in central Gaza, and witnesses said Israeli tanks and infantry were approaching Khan Younis in the south.

The Israeli army said three of its soldiers were killed by a shell from an Israeli tank which hit their position.

A fourth Israeli soldier was killed in fighting in the north of the Gaza Strip, possibly also by fire from his own side, military officials said.

At least three Palestinians were killed on Tuesday when an Israeli air strike hit a United Nations school in the Gaza Strip where about 400 people were sheltering, UN officials said.

Other people were killed as Israeli shell-fire and air strikes hit the Gaza coast, Gaza City and Jabaliya refugee camp in the north of the territory.

Information about what is happening inside Gaza is limited as Israel has barred foreign reporters from entering.

'In shock'

The United Nations also warned that the humanitarian crisis in Gaza would deepen as it was having difficulty getting aid into the territory.

The UN Relief and Works Agency (Unrwa) said it would be unable to bring in 80 lorries of humanitarian supplies scheduled for Tuesday after the head of the company contracted to transport the supplies lost three relatives, including one son, in attacks on Monday night.