China's top quality regulator, Li Changjiang, has stepped down over a growing tainted milk scandal that has already hospitalized 53,000 children and killed four.

The official Xinhua news agency says China's cabinet, the State Council, approved the resignationMonday.

Li heads China's General Administration of Quality Supervision, Inspection and Quarantine, which is responsible for the safety of the country's food supply chain.  He will be replaced by Wang Yong, former deputy secretary-general of the State Council.

The chemical melamine has been found in infant formula and other milk products from 22 of China's dairy companies.

China's Health Ministry says nearly 13,000 children remain hospitalized from drinking tainted milk, with 104 in critical condition.

China says about 80 percent of the children affected are no more than two years old.

In the first reported case outside mainland China, health officials in Hong Kong confirmed Saturday that a three-year-old girl has developed severe kidney problems. 

The girl became ill after drinking a contaminated Chinese-produced milk beverage for the last 15 months.

Hong Kong authorities have also found a small amount of melamine in Chinese-made Nestle brand milk. Melamine can cause foods - such as watered-down milk - to appear to be higher in protein.

Countries in South Asia, East Asia and Africa have banned milk products from China.  Burmese authorities are promising to seize and destroy Chinese milk products.

Eighteen people have been arrested in connection with the milk scandal.

Some information for this report was provided by AP.