DAKAR—The terms of China’s loan deals with developing countries are unusually secretive and require borrowers to prioritize repayment of Chinese state-owned banks ahead of other creditors, a study of a cache of such contracts showed on Wednesday. The dataset—compiled over three years by AidData, a U.S. research lab at the College of William & Mary—comprises 100 Chinese loan contracts with 24 low- and middle-income countries, a number of which are struggling under mounting debt burdens amid the economic fallout from the COVID-10 pandemic. Much focus has turned to the role of China, which is the world’s biggest creditor, accounting for 65 percent of official bilateral debt worth hundreds of billions of dollars across Africa, Eastern Europe, Latin America and Asia. “China is the world’s largest official creditor, but we lack basic facts about the terms and conditions of its lending,” the authors, including Anna Gelpern, a law professor at Georgetown …