BEIJING - The number of children in China sickened by dairy products tainted with the banned industrial chemical melamine has jumped to nearly 53,000, the government said Sunday as it vowed to crack down on those responsible for one of China's worst food safety scandals in years.

More than 80 percent of the 12,892 children hospitalized in recent weeks were 2 years old or younger, the Health Ministry said in a statement posted on its Web site late Sunday. Four children have died and 104 of the hospitalized children are in serious condition.

Another 39,965 children received outpatient treatment at hospitals and were considered "basically recovered," the ministry said.