"We will transport 550 patients in 40 Palestinian ambulances and five trucks. All of them have official medical referrals from the health ministry," said the director of Gaza emergency services, Dr. Muawiya Hassanein.

The patients include 200 people wounded in Israeli military operations and 70 children under the age of 16, he said.

A senior Hamas official confirmed that the crossing would be open for three days to allow the sick to enter for treatment and those trapped on one side or the other to cross back to their place of residence.

"The Rafah crossing will be open for three days beginning on Saturday for emergency cases, in the context of easing the suffering of our people and based on coordination between Hamas and Egypt," Ismail Radwan told AFP.

"We hope this will be the first step towards permanently opening the crossing and breaking the siege," he said.

Since the Islamist Hamas movement seized power in Gaza nearly 11 months ago, taking over the entire government including the health ministry, Israel has sealed Gaza to all but very limited humanitarian assistance.

Some 25 ambulances lined up on the Gaza side of the border as dozens of black-clad Hamas police patrolled the crossing, keeping crowds away from the area.

"We hope Rafah will stay open like before. The health situation in Gaza is very serious. There is no medicine, nothing," said Mufid Habush, as he waited at the crossing with his five-year-old daughter.

The little girl, whose leg was amputated because of a birth defect, was due to have an operation in Egypt.

Adham Dawas, 42, lay in an ambulance nearby. "I've had throat cancer for 11 years. I went to Jordan, to Iraq, to other countries, but nobody can cure me," he said, adding that he has had a permit to leave for four months.

For months, Hamas has been calling on Egypt to open the Rafah border crossing -- the only gateway to Gaza not under Israeli control -- but it has done so on only a few occasions since last summer.

In January, Gaza militants blew open large sections of the border fence, sending hundreds of thousands of Palestinians pouring into Egypt to stock up on basic goods.

Egyptian and Hamas forces later sealed the border, leaving some 500 Egyptians, mostly women and children, stranded in Gaza. On Sunday they were to be allowed to return, and Gazans were to be allowed back from Egypt on Monday.

Fatima, a 30-year old Egyptian, and her five children, sat on a pile of luggage with dozens of other people, hoping they would be allowed to cross early.

"I came to see my mother in January but I couldn't go back to Egypt. Today I came in the hope they will let me cross," she said.

At the end of last month, Egypt secured a ceasefire proposal from 12 Palestinian factions, including Hamas, which would include the opening of the crossings. Israel has yet to formally respond to the offer.

© 2008 Agence France-Presse