Eight Palestinian unity government ministers are to travel to Gaza from its West Bank base on Monday for only the second time since its formation in June, a minister said.

Hamas on Sunday prevented dozens of children orphaned during its 50-day war with Israel from entering Israeli territory in a pre-arranged trip, organizers and officials said.

The week-long visit was planned for 37 children whose parents were killed by Israel in the Gaza Strip in July and August this year. It was organised by an Israeli kibbutz group and local Arab-Israeli officials.

Israel launched an air strike in southern Gaza on Wednesday and killed a Hamas militant after a sniper attack on a patrol seriously wounded a soldier, the army and medics said.

It was only the second time Israel had struck Gaza since a 50-day war ended with a truce on August 26, after witnesses reported a first strike early on Saturday.

Egypt kept its Rafah border crossing with Gaza open for a third day on Tuesday, state media said, after nearly 2,000 people used the terminal in the first two days.

The Rafah crossing, the only access point to the Gaza Strip not controlled by Israel, opened on Sunday for only the second time in two months to allow people stranded in Egypt to enter the Palestinian enclave.

Barely four months after a bloody conflict battered Gaza, experts warn that a new war could be in the offing if reconstruction is not accelerated and Palestinian divisions remain.

Since the end of the deadly 50-day war between Israel and Hamas, which killed nearly 2,200 Palestinians and 73 in Israel, little has changed on the ground in Gaza.

Around 630 Palestinians left Gaza and entered the Egyptian Sinai through the Rafah crossing on Sunday after Cairo authorized a temporary reopening of the border, a Palestinian official said. 

Israeli air planes struck targets in the southern Gaza Strip, witnesses and the army said early Saturday, hours after a rocket from the Palestinian enclave hit the Jewish state.

A spokesman for Gaza's health ministry said there were no casualties in the attack, the first air strike by Israel on the Palestinian enclave since the summer truce that ended the deadly 50-day war between the sides.

The U.N. warned Thursday it was running out of funds to house families in Gaza, as it doubled its estimate of the number of homes damaged or destroyed in this summer's war with Israel.

"Unless the situation changes urgently, we will run out of funds in January, meaning we will not be able to provide rental subsidies to many affected families nor provide the support required to carry out repairs," said Robert Turner, the operations director for the UNRWA Palestinian refugee agency.

Thousands of supporters of exiled Palestinian strongman Mohammed Dahlan protested Thursday in Gaza against the reported sacking of dozens of members of the security forces who back him.

A small Islamic militant group claimed responsibility Thursday for a bomb attack that slightly damaged the French Cultural Center in Gaza City last week without causing any casualties.