HONG KONG - At least 12 countries -- from Indonesia to Colombia -- have banned Chinese dairy products amid fears over a widening tainted milk scandal that has killed four Chinese babies and sickened thousands of others.

Worries that compromised ingredients may have contaminated other foods like yogurts, cookies and candies have led several more countries, from Canada to Australia, to step up testing of Chinese imports.

The health scare has hit hardest in Asia, where nervous parents have rushed their children to hospitals for health checkups in recent days after China revealed that baby formula laced with a toxic chemical had sickened 54,000 infants.

"I'm still worried about my child," said Mary Yu, a Hong Kong mother who took her 3-year-old son for hospital tests Tuesday, along with hundreds of other parents in the territory. "I want to have a thorough check to play it safe."

As the reports of sick babies multiplied -- with at least five reported outside the mainland in the Chinese territories of Hong Kong and Macau -- even countries that don't import Chinese dairy began sounding alarms.

The European Union urged customs authorities on Monday to intensify checks on imports of "composite products," such as bread or chocolate, to ensure they contain no traces of contaminated milk.

Growing public fears prompted some schools and stores to pull more products as a precaution. Even major international food makers such as Kraft Foods were hit by unconfirmed rumors of recalls of numerous snacks, including Oreo cookies and M&Ms.

The crisis was initially thought to have been limited to Chinese milk powder laced with melamine, an industrial chemical used to make plastics and fertilizer that can cause kidney stones and lead to kidney failure.

But recent testing found melamine in samples of liquid milk taken from 22 Chinese companies -- including the country's two largest dairy producers -- and spurred nationwide recalls of milk and dairy products.

Since the scandal broke two weeks ago, Bangladesh, Brunei, Japan, Malaysia, Philippines, Singapore, Taiwan, Burundi, Kenya and Gabon have placed at least partial bans on Chinese dairy imports or foods that may contain milk. Vietnam has ordered testing of all Chinese milk products and pulled several thousand litres of milk from supermarket shelves.

On Wednesday, Indonesia issued a sweeping ban covering 28 products -- everything from liquid milk to Oreos and Snickers -- out of concern they might be poisoned with adulterated Chinese dairy.

"The government has banned those products as a precaution even though we have not tested them yet," said Tien Gardini of Indonesia's food regulatory agency.

Colombia, which had not imported powdered milk or baby formula from China, specifically prohibited the import of all Chinese powdered milk and any products derived from it last week.

As import bans continued to crop up, the World Health Organization warned Tuesday that the tainted infant formula at the heart of the scandal might be smuggled across borders.

"I think the greatest fear is if there has been illegal movement of the heavily contaminated products rather than the legal movement of products that may have very low levels of melamine," said Anthony Hazzard, a WHO adviser on food security.

France heeded the call, saying it was checking to make sure no Chinese baby milk products have slipped into the market on a small scale.

But most consumers and regulators were focusing on legal imports.

Canada issued recalls for Mr. Brown brand instant coffee after Taiwan pulled the product off its shelves. Bangladesh ordered testing of powder milk imported from countries known for tighter government regulations such as Australia, New Zealand and Denmark.

Malaysia expanded its ban on Chinese milk products on Tuesday to include candies, chocolates and any other food containing milk.

With consumer confidence shaken, international food makers were put on the defensive.

A major Japanese food maker, Marudai Food Co., pulled its cream buns, meat buns, and creamed corn crepes from supermarkets, but was still conducting tests.

After reports that a 16-month old in Macau developed a kidney stone after drinking Chinese-made Nestle milk powder made, the company rushed to assure consumers its products hadn't been affected.

Switzerland-based Nestle said in a statement Tuesday that its milk products sold in China and Hong Kong are "absolutely safe." No government tests have found melamine in Nestle milk products.

U.S.-based Kraft Foods Inc. issued a statement saying Oreo products with milk do not contain any dairy from China. A spokeswoman for Mars, maker of M&M candies and other sweets, said the company doesn't source any ingredients from China's blacklisted firms.