RIYADH — An operation to separate Yemeni conjoined twins will be held at King Abdullah Specialist Hospital for Children here on Friday. The operation for the children, Abdul Aziz and Abdullah, will be conducted in line with the directives of Custodian of the Two Holy Mosques King Salman, the Saudi Press Agency reported. The operation will be the 37th of its kind carried out in the Kingdom to separate conjoined twins. Dr. Abdullah Al-Rabeeah, adviser at the Royal Court and general supervisor of King Salman Center for Relief and Humanitarian work, said a 30-member medical team headed by him would carry out the operation. There will be eight phases for the operation, which is expected to take about 12 hours. He said Abdullah is suffering from life-threatening physical birth defects related to his head, heart, kidney and hands. The twins were brought to the Kingdom more than 15 months ago and they have undergone several checkups and treatment at King Fahd Medical City and King Abdulaziz Medical City under the Ministry of the National Guard, Al-Rabeeah said.