Dairy giant Fonterra's products at the centre of a global contamination scare this month did not contain a bacteria that could cause botulism, and posed no food safety threat, New Zealand officials said on Wednesday.

The Ministry for Primary Industries (MPI) said tests showed whey protein concentrate had clostridium sporogenes, which cannot cause botulism, but which at elevated levels can be associated with food spoilage.

Original tests raised fears the whey protein concentrate, used in infant formula and sports drinks, might contain clostridium botulinum, which can cause potentially lethal botulism.

"We sought additional testing at both local and international laboratories, seeking the most robust results we could get. Scientists used a range of methods - all came back negative for clostridium botulinum," said acting MPI director General Scott Gallacher. "(The) MPI has today informed overseas regulators of these results and we will be providing them with a full diagnostic report shortly."

The latest test results tally with Fonterra's own initial testing, which pointed to clostridium sporogenes.

The botulism scare triggered a recall of Fonterra products that may have contained the whey protein in a number of markets, from China and Australia to the Middle East and Southeast Asia. It also prompted bans in Russia and Sri Lanka, while other countries stepped up scrutiny of the company's dairy products. Fonterra said on Wednesday it resumed operations in Sri Lanka.

There was no immediate comment on the MPI test results from Fonterra, which controls about a third of the world's dairy exports, but the company had urged that the MPI results be released to counter negative market talk before the ministry statement was issued.

Fonterra shares were suspended from trading earlier on Wednesday.

Fonterra has said the contaminated whey protein concentrate was caused by a dirty pipe at one of its processing plants. - Reuters