The United Nations agency for Palestinian refugees is warning that it may not be able to cope with the number of people made homeless by Israeli army demolitions.
By James Rodgers
BBC Gaza correspondent
The head of the organisation, Peter Hansen - on a visit to the southern Gaza Strip - condemned Israel's policy of demolishing houses as a hugely disproportionate military response.
The UN says it cannot cope with the scale of demolition in Gaza
Mr Hansen was jostled by an angry crowd, who said that the UN should have rebuilt homes where they were destroyed.
In Rafah, near the Egyptian border, Israeli troops destroyed buildings which they say have been used as firing positions, or to conceal tunnels for smuggling weapons.
While not disputing that this was true in some cases, Mr Hansen said that the scale of demolition could not be justified.
According to UN figures, almost 600 people have been made homeless in the Rafah refugee camp since 16 January.
Since October 2000, more than 14,000 people in the Gaza Strip have lost their homes - almost 10,000 of them in Rafah.
Mr Hansen is now warning that the UN's resources are being stretched almost to breaking point.
"We can simply not keep up with this," he said. "We will need some $30m to make sure that all of the people who have lost their homes will be able to have a replacement home."
The frustration felt in Gaza's poorest and most dangerous areas boiled over.
Arriving for a planned ceremony to hand over new houses, Mr Hansen was jostled by an angry crowd who argued that the buildings should have been put up where the old ones were demolished.
That is not possible, says the UN, arguing that the replacement homes would themselves just be destroyed shortly afterwards.