New Zealand's Fonterra, the world's largest dairy exporter, said on Saturday it had found bacteria which can cause botulism in some of its dairy products, prompting China to recall affected products.

New Zealand authorities said they were holding back some widely used infant formula products from supermarket shelves.

Fonterra said it had sold New Zealand-made whey protein concentrate contaminated with Clostridium Botulinum to eight customers, including food and beverage companies and animal stock feed firms, for possible use in infant formula, body building powder, and other products. None of its own branded products were affected, it said.

The Ministry of Primary Industries said Fonterra had told it the products in question were exported to Australia, China, Malaysia, Vietnam, Thailand and Saudi Arabia.

China, which imports most of its milk powder from New Zealand, asked domestic importers to recall any products which may have been contaminated by the bacteria, and ramped up scrutiny of New Zealand dairy products coming into the country.

Fonterra, New Zealand's largest company has been planning to launch its own branded milk formula in China, five years after melamine-tainted infant formula killed at least six there and made thousands ill.

Russia has suspended imports and circulation of Fonterra products, Russian ITAR-TASS news agency said on Saturday, quoting the country's consumer watchdog Rospotrebnadzor.

China's product safety agency said it had asked New Zealand to take immediate measures to "prevent the products in question from harming the health of Chinese consumers".

Clostridium Botulinum is often found in soil. The Fonterra case was caused by an unsanitary pipe at a processing plant.

The Ministry of Primary Industries said five batches of Karicare formula manufactured in New Zealand for babies aged six months and older were produced using the contaminated product.

Karicare is made by Nutricia, which operates in New Zealand, and supplied by Fonterra. The brand is popular in China.

The MPI said it had been informed by Nutricia that one batch was on a ship, another was in storage in Australia, while the remaining three were in a warehouse in New Zealand.

Fonterra is a big supplier of wholesale milk powder to Chinese dairy firms and also supplies multinational food and beverage companies.

Foreign-branded infant formula is a prized commodity in China, where consumers are distrustful of domestic brands given a series of food safety scandals. Popular foreign brands include Nestle, Danone and Mead Johnson.

The U.S. Dairy Export Council has issued the following statement:

"Fonterra and the New Zealand government have isolated the affected product, have taken steps to remove it from the supply chain, and have identified the cause of the problem to an unsanitary pipe that wasn’t correctly sterilized.

"U.S. dairy products are not involved.

"There have been no reports of any illness linked to the consumption of the affected whey protein and there is no current information to suggest that U.S. food products are affected."