BEIJING - China's Communist Party chief, Mr Jiang Zemin, has barred his predecessor, Mr Zhao Ziyang, from returning to Beijing from the provinces, fearing a challenge to his grip on power, Chinese sources said yesterday. Mr Zhao, who was in the eastern city of Hangzhou when Deng Xiaoping died on February 19th, had sought permission to return to the capital to attend the funeral rites but Mr Jiang vetoed the plan, sources said.