Water supplies in a central China city have resumed after water contamination in a local river forced the suspension of three water suppliers on Wednesday.

The Baihezui, Yushidun and Guomian water plants in Wuhan, capital of Hubei, all resumed water production as of 6 p.m., local authorities said.

The three major water manufacturers in the city stopped supplying local people after tests showed that the Wuhan section of the Han River, a major tributary of the Yangtze River, contained excessive amount of ammonia and nitrogen.

Their moratorium on water supplies caused a water shortage in an area of 260 square km in the city, affecting hundreds of food manufacturers as well as the livelihoods of more than 300,000 people, the city government said in a statement.

Local departments have been testing the river water every half an hour, while environmental protection bureaus at the provincial and city levels are still identifying the source of the pollution.

The accident came less than two weeks after a water contamination case in Lanzhou, capital of northwest China's Gansu Province, triggered public panic.

On April 11, the Lanzhou city government warned residents not to drink tap water for 24 hours, after more than 10 times the national standard of benzene was found in the tap water. The pollutants are believed to have leaked from a pipeline of Lanzhou Petrochemical, a subsidiary of China National Petroleum Corporation, the country's largest oil company.