China has halted imports of all milk powder from New Zealand and Australia, New Zealand's trade minister said on Sunday, after bacteria that can cause botulism found in some dairy products raised food safety concerns that threatened its $9.4 billion annual dairy trade.

Global dairy giant Fonterra identified eight companies to which it had sold contaminated New Zealand-made whey protein concentrate, exported to China, Malaysia, Vietnam, Thailand and Saudi Arabia and used in products including infant milk powder.