Rebuilding the Gaza Strip after Israel's three-week offensive will cost billions of dollars, the UN has warned.
Tens of thousands of Palestinians have been left homeless and 400,000 people still have no running water, it says.
Reports say UN Secretary General Ban Ki-moon is travelling to Gaza on Tuesday to inspect the damage.
A fragile ceasefire between Israel and Hamas militants is holding, allowing many Palestinians to return home to assess the damage.
Israel called a ceasefire on Saturday, saying it had met its war aims. Hamas later declared its own truce, with one of its leaders claiming a "great victory" over Israel.
Israeli Prime Minister Ehud Olmert has said he wants troops to leave Gaza "as quickly as possible" and some have already left.