The agency is already providing shelter for more than 1,000 displaced Palestinians at schools it runs in southern and northern Gaza.
Seven soldiers also were wounded Thursday in southern Gaza, five of them when their jeep was hit by an antitank missile, the army said.
For at least the next six months, Israel will continue to check everyone entering or leaving southern Gaza.
There is also the real possibility of factional fighting, already scattered in southern Gaza.
Nor do they know whether this cooperative farming community of 26 families in southern Gaza will be able to stay together, as its members would like.
The cousins' mangled bodies were returned today to this struggling town in southern Gaza.
But in southern Gaza where they withdrew tanks, they built four new watchtowers and a military post, the official said.
Another Palestinian, a boy of 16, died after being shot near Rafah in southern Gaza.
Israeli troops have taken up positions in southern Gaza, but have not engaged in serious fighting.
In southern Gaza, a pregnant woman and her brother were shot dead, Palestinian security officials said.