Fonterra chief executive Andrew Ferrier says it was “absolutely gut-wrenching” knowing for six weeks that poisoned milk sold by his company’s Sanlu joint venture was still in people’s homes and being fed to Chinese children.

“We will never know, if we had gone public at the beginning, whether it would have made a difference at that time,” he said on Friday.

The death toll in the contaminated baby formula crisis in China has risen to four, with the death of a baby in northwestern Xinjiang Uygur autonomous region, local authorities said on Friday. Three other babies, including two in northwestern Gansu Province and one in eastern Zhejiang Province have also died.

Over 6000 Chinese children have been poisoned by milk adulterated by melamine, a chemical used to cover up dilution of the raw milk. Most have suffered kidney damage, with nearly 160 seriously ill, and three deaths so far. The chemical was first found in Sanlu’s “Bei Bei” infant milkpowder but has since turned up in product lines of 22 other companies in China.

Fonterra said its three directors on the Sanlu joint venture’s board were told of the contamination on August 2, and that it unsuccessfully urged the company and local politicians to announce a public recall.

But it decided instead to work within the system, with an unannounced “trade recall” from shops and warehouses. The contamination was eventually announced when the Chinese government launched an investigation last week, and Fonterra made its first public comment on September 14.

Asked on Friday if his conscience was clear, Ferrier said it was not a question of whether his conscience was clear, but whether the company did the right thing.

“But I can tell you, every day, every day, people were asking: are we doing it the right way?

“It was absolutely gut-wrenching: this is as bad as it gets in food companies.”

The focus had been to make it better any way it could by getting the product off the shelves.

“You always say: `what could we have done differently?’,” Ferrier said.

He had been “tremendously relieved” when the Chinese government backed a public recall of Sanlu product last week, but said it was unclear whether the Chinese began the public recall before or after the New Zealand Government warned it of the contamination earlier in the week.

“We were just tremendously relieved the public recall happened.”

Ferrier said he was not angry over the food safety crisis, but was “demoralised”.

“The fact that it happened is just a tremendously tragic event.”

The company’s duty of care now to its customers involved praying that the children recovered their health, he said.