Four out of 7 patients, including foreign visitors, who had liver transplants died within one month after the surgery at a new hospital in Kobe established in November, the Yomiuri Shimbun said Tuesday.

The hospital, Kobe International Frontier Medical Center, transplanted livers of the patients' relatives between December and March. After the surgery, two Indonesian and two Japanese patients who had suffered from biliary atresia died after their kidneys and livers malfunctioned. Two of the patients were under 15 years old.

The high mortality rate prompted experts to call on the hospital to stop such surgery. The Japanese Liver Transplantation Society, a group of doctors specializing in liver transplants, has started to investigate if treatment at the hospital is appropriate.

Part of Kobe's project to become a city strong for medical business, the hospital features advanced medical services, including liver transplants for patients coming from overseas.