Israel says it will allow a number of Palestinians who have been trying to flee the Gaza Strip to enter Israel for urgent medical treatment.
They are among dozens of people stranded at the Erez border crossing for days - some in a desperate state.
They have been trying to flee Gaza after it was taken last week by Hamas militants from their rivals Fatah.
The UN says food supplies in Gaza will be exhausted in seven to 10 days unless Israel allows normal shipments through.
It has 100 container loads with supplies ready at the Karni border crossing.
Palestinian Authority President Mahmoud Abbas is due to address a meeting of the central committee of the Palestine Liberation Organisation (PLO) in the West Bank city of Ramallah on the situation on Wednesday.
His new emergency government that excludes Hamas has received strong international backing - the US and the EU have lifted a financial and diplomatic embargo imposed after Hamas won elections and came to power 18 months ago.
At one point, there were up to 600 Gazans sheltering inside a long dusty concrete tunnel on the south side of the crossing.
It is not clear how many are still there - with reports ranging from 70 to more than 200.
There are no facilities to sustain life, and many people have been left lying there on the bare concrete amid their own filth.
Israel's Physicians for Human Rights has sent a petition to the Supreme Court to force the authorities to offer immediate medical treatment to those needing it.
And new Defence Minister Ehud Barak has now instructed officials to admit those needing urgent care.
Among the first being allowed in shortly after Mr Barak's order was a 17-year-old boy with leukaemia, the Associated Press news agency quoted Shadi Yassin, a military liaison official, as saying.
Most people fleeing have been denied entry by Israel, which controls the crossing, on security grounds.
Some were believed to be members of pro-Fatah security forces - they fear Hamas militants, despite an amnesty issued by Hamas after the takeover.
An Israeli spokesman said on Wednesday that they should return home.
"There is no obstacle to their returning home, and the fact of the matter is that most of them have already done so. Hamas also declared that it had not intention of harming them and released most of the detainees," Peter Lerner, told Israel army radio.
Foreign nationals were also reported to be leaving Gaza - including a group of about 140 Russian citizens.
For the first time since Hamas took over, Israel said it had launched air strikes on rocket-launching sites in northern Gaza after one rocket hit near the Israeli town of Sderot, the army said.
There are no reports of casualties.
In a separate incident, Israeli troops killed four militants in the south of the coastal strip near the Kissufim border crossing - two members of Hamas and two other militants.
Two more Palestinian militants were killed in a clash at a village near the West Bank town of Jenin.
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