BBC News website, Jerusalem
The United nations has warned of an increasingly desperate humanitarian situation in the Gaza Strip as Israel's offensive in the territory continues.
Water supply problems are raising are a serious public health risk
The Israeli military says the operations aim to stop Palestinian rocket fire and gain the release of a captured soldier.
"The situation is dangerous and desperate," says John Ging, the head of operations of the UN agency which assists Palestinian refugees.
"The Palestinians are struggling to survive; their preoccupation is security, water, food and electricity. It doesn't get any more basic than that.
"The situation in many areas is quite disgusting in terms of the living conditions and it continues to deteriorate."
Rolling power cuts are affecting water supplies and sewage plants in the territory risking public health, the UN says, after an Israeli air strike knocked out Gaza's only power plant.
The Coastal Municipality Water Utility is now relying on its backup generators to operate its 130 water wells and 33 sewage pumping plants.
160% increase in cases of diarrhoea compared with the same period last year (Source: WHO)
In June 70% of the Gazans were already unable to cover their daily food needs without assistance, food is an increasingly critical issue (Source: WFP)
A shortage of fuel has meant the plant has cut its daily operations by two thirds and raw sewage is being pumped out into the sea.
"A humanitarian and health catastrophe is inevitable if we don't get fuel," Gaza Mayor Majed Abu Ramadan told Reuters on Monday.
"We may even witness sicknesses which we have not seen for a long time, such as cholera."
Fuel shortages have cut rubbish collection services, with black bags of waste piled high in many streets in Gaza City.
Hospitals in Gaza are using generators to run medical equipment but they have only two weeks of fuel left, according to the World Health Organization.
It also said that 23% of the essential drug list will be out of stock within a month.
In Gaza's northern town of Beit Lahiya, Israeli troops withdrew on Saturday leaving churned-up roads and broken water pipes.
Residents could be seen fitting pumps to the burst pipes to carry water into their houses.
Aid agencies are also warning about a food shortage in the territory.
According to the UN, there are 230 cargo containers of food sitting on the Israeli-Gaza border which they have not been allowed to take into the territory.
Israeli Prime Minister Ehud Olmert said on Monday Israel was still supplying Gaza with water and electricity.
"The reason we are is that we care for the population and we don't want to punish the civilian population," Mr Olmert said.