NANJING - Rescuers are combing city sewers for a 3-year-old boy who has been missing since he fell down a manhole in East China's Jiangsu province on Thursday, local officials said Saturday.

The boy has been missing since 8 pm Thursday, when he disappeared into a six-meter-deep hole in the city of Xuzhou, the city government said in a statement.

More than 50 rescuers and specialists have been searching the city's sewage system since the accident, but they said the fast-moving currents and high water levels have hampered rescue efforts.

The accident was the latest involving a manhole since the case of Yang Lijun, 21. A high-profile manhunt was launched after she fell into an uncovered hole in Changsha, capital of Hunan province, during a storm in March. Her body was found in a river about two months later.

Police are still investigating the case.