Less than two weeks old, Ritaj and Rittal Abu Assi arrived on Tuesday at the hospital, which has a center specializing in conjoined twins.

But a hospital spokesman said their condition was still too poor to decide on moving ahead, and that their conjoined heart had a “serious defect” which poses a big problem for any surgery.

“Tests confirmed that the condition of the twins Rital and Ritaj is very critical and their health is not stable,” said hospital spokesman Sami Al-Shalan.

Doctors “are still studying the case,” and are waiting to see if their condition improves, he added.

“They are conjoined at the heart, two hearts joined as one heart, and there is a big defect in the heart. This is inseparable,” he said. The twins were allowed to leave Gaza Tuesday through Egypt and were flown to Riyadh under the sponsorship of Custodian of the Two Holy Mosques King Abdullah.

The twins were born on March 27 in the Gaza city of Khan Younis, where available medical facilities were inadequate for their case as a result of the Israeli-Egyptian blockade.

They were examined on arrival in Riyadh by a medical team including Health Minister Dr. Abdullah Al-Rabeeah, who has personally carried out many of the separation surgeries undertaken at King Abdul Aziz Medical City.

To get to Riyadh, the tiny, 11-day-old girls had to overcome a string of obstacles: blockaded borders, squabbling governments and holiday restrictions in Israel and Egypt.

On birth, they weighed four kilograms (8.8 pounds), said Gaza doctor Ayman Abu Amouna, who treated them.

The birth sparked curiosity in Gaza, and doctors from around the territory came to see a condition they had only read about in books, said Mohammed Al-Kashif of Gaza’s Health Ministry.

“This is a very rare and strange case,” he said. “The doctors have never seen anything like it.”

Al-Kashif said the girls’ birth was the first of conjoined twins on record in the Palestinian territories. A spokesman for the West Bank-based Palestinian Authority’s Health Ministry concurred.

King Abdullah heard about the twins through the media and ordered they be brought to the Kingdom for surgery, said Ahmad Al-Sedairi, the Saudi ambassador to Egypt. The king has funded such surgeries in the Kingdom from other parts of the world.

The twins, who are accompanied by their parents, were received at the hospital by Al-Rabeeah and Dr. Bandar Al-Knawy, chief executive officer (CEO) of the National Guard Health Affairs and president of the King Saud bin Abdulaziz University for Health Sciences, and senior KAMC surgeons.

Formerly known as the National Guard Hospital, the Riyadh hospital has handled 58 conjoined twin cases since 1990, successfully separating 25.

— With input from agencies