Transfusions at public hospitals in Hong Kong were halted for five hours yesterday after kits used to test blood donations for syphilis were found to be faulty. The kits had been used to test more than 68,000 donations between June and this month. Health officials estimated that between 2,000 and 3,000 patients, many suffering from cancer, would have received blood products manufactured from the 68,000 donations. But they said the risk of contracting the disease was remote.