RIYADH, 16 September — A surgery to separate Malaysian Siamese twins, conjoined at the stomach, will be performed at King Abdul Aziz Medical City here tomorrow.

This was disclosed by Dr. Abdullah Al-Rabeea, deputy executive director of health affairs at the National Guard, at a press conference.

“The complex operation will take at least 15 hours. After the operation the twins will remain in the intensive care unit for about two weeks and under observation for about two to three months,” Rabeea told reporters.

Answering questions , Rabeea and the hospital’s doctors said the twins would be able to lead a normal life after a successful operation, which is to cost about SR1.5 million. The medical city has already successfully separated two sets of conjoined twins.

The twins, named Ahmad and Mohammed Rahman, accompanied by their father Roush ibn Abdullah Rahman, 31, and mother Aysha arrived here about two weeks ago.

Prince Abdullah, the regent, had made arrangements to separate the twins and treat them at the Saudi hospital, when their parents failed to raise the cash required for the operation in London.

Aysha, the twins’ mother, said she was worried about the operation but expressed confidence in the ability of Saudi surgeons. Doctors in Malaysia had told the couple that the twins would require at least five operations to separate them.