GENEVA -- The World Health Organization (WHO) is confident that the Chinese government has provided timely information on the tainted milk problem, a WHO spokeswoman said on Tuesday.

"We don't really know the scale of the problem, but we are confident that the Chinese authorities are informing us in a timely manner," Fadela Chaib told a news briefing in Geneva.

WHO said nearly 40,000 cases of kidney stones in infants with three confirmed deaths related to the consumption of melamine-contaminated powdered infant formula have been reported from across China as of September 21. Almost 12,900 are currently hospitalized.

According to the spokeswoman, China is not obliged to inform WHO of this case because it is a nationwide problem, not an emergency with an international impact or scale.

WHO is therefore awaiting the results of a full investigation by the Chinese authorities to learn the scale of the problem, she said.

She added that it was not clear if the peak of the crisis had been reached or not. As more and more rural families in China become aware of the problem they are bringing their children to hospitals for check-up.

Meanwhile, a WHO expert said Tuesday that the organization saw no need for an import ban on Chinese milk products.

Up to now WHO has not received reports of infants in other countries affected by tainted milk produced in China, said Danilo Lo-Fo-Wong, a senior scientist in WHO's food safety division.

WHO is concerned with public health in all member states but "does not recommend to just ban all Chinese milk products, at least not at this stage," he said.