BEIJING (AFP) - - More than 3,600 babies remain in hospital in China after drinking tainted milk products that have sickened over 53,000 children, the government said Thursday.

Of the 3,654 infants still in hospital, three remain in serious condition, while over 46,700 children have recovered and been released from medical clinics as of October 22, the health ministry said in a short statement.

On Tuesday, 105 young children were admitted to hospitals around China with kidney ailments stemming from drinking the tainted milk products, while 370 infants were released, it added.

The ministry did not report any new fatalities, but said that the four infant deaths so far attributed to drinking the contaminated milk all occurred between May and August before the scandal was made public.

The government had previously reported that more than 53,000 children had fallen ill after drinking tainted milk.

The scandal erupted when melamine , an industrial chemical normally used to make plastic, was discovered in Chinese-made dairy products, including milk powder, liquid milk and yoghurt.

The chemical was added to watered-down milk to make it appear higher in protein, but led to kidney stones developing in the infants.

The scandal has hit China's dairy industry hard, and continues to escalate around the world as multinationals and countries recall made-in-China milk products.

On Wednesday, the United Nations urged China to modernise its food safety system arguing that an outdated and disjointed approach may have worsened the crisis.

Although at least one Chinese dairy firm knew of the scam for months, it did not immediately report it to local government officials, who in turn delayed passing on the news for nearly a month until after the August Beijing Olympics.