Story highlights China halts imports of milk powders produced by a New Zealand company

The import ban comes after a botulism-causing bacteria was found in the product

Milk-powder maker Fonterra is the world's largest exporter of dairy products

No reported illnesses yet; Fonterra says it's working with client companies

China has halted imports of some New Zealand milk powders after a company disclosed that three batches of an ingredient used in sports drinks and baby formula tested positive for a strain of bacteria that causes botulism.

The New Zealand-based Fonterra Group said Saturday that three batches of its whey protein tested positive for the Clostridium botulinum bacteria. Those batches weren't for use in Fonterra-branded products, but they said companies that used the whey protein in their products might issue recalls.

Fonterra, the world's largest dairy exporter, said it had warned companies that bought the whey protein about the problem. "As a result, these customers are urgently investigating whether any of the affected product, which contains a strain of Clostridium, is in their supply chains," the company said.

Three of those clients have told Fonterra that their products are safe.

"Our technical teams have been working closely this weekend with Coca-Cola, Wahaha and Vitaco and have established that the process used to manufacture their products would kill the bacteria that was in the affected whey protein concentrate," Gary Romano, Fonterra's managing director of NZ Milk Products, said in a company statement.

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But China -- where at least six babies died from tainted milk powder in 2008 -- has halted all imports of New Zealand milk powders from New Zealand and Australia, New Zealand's Trade Minister Tim Groser said in an interview on television network TVNZ on Sunday.

But in an update on its website, the New Zealand Ministry for Primary Industries clarified that Chinese authorities had suspended imports of Fonterra-produced Whey Powder and Dairy Base powder, while also increasing inspection and supervision of New Zealand dairy products.

"China has not closed the market to all New Zealand dairy products," the ministry said. "And it has also been quite specific about the range of Fonterra products which it has temporarily suspended."

Dairy is a key industry in New Zealand, making up about 3% of its GDP.

The Trade Ministry said Australia, Malaysia, Saudi Arabia, Thailand and Vietnam also imported the product.

Botulism can be fatal, with symptoms typically beginning within 36 hours of consuming contaminated food. The infection can result in paralysis and respiratory failure, according to the U.S. National Institutes of Health

The company involved, Sanlu Group, was partially owned by Fonterra . Sanlu group later filed for bankruptcy.