A medical team in Saudi Arabia on Monday successfully separated a pair of Polish conjoined infant girls who shared a spine and intestines.

The twins, 14-month-old Daria and Olga Kolacz, underwent a complex 15-hour separation operation at the King Abdul Aziz Medical City in the capital Riyadh.

“They have been successfully separated,” said Doctor Abdullah al-Rabeeah, who carried out most of the surgery.

“There were no complications. Our expectation is that they will do well but there will be many days to come which are critical.”

Rabeeah said doctors were still performing reconstructive surgery on the twins, which should be completed within a couple of hours.

Saudi Arabia’s de facto ruler Crown Prince Abdullah paid for the surgery. A Saudi doctor brought the case to Prince Abdullah’s attention after he learned about the twins from an Internet chat room.

The procedure was the sixth of its kind at the Riyadh hospital and the ninth in the kingdom.