Italian Agriculture Minister Gianni Alemanno demanded tests to see if babies given the contaminated milk over a prolonged period faced health risks.

"It is incredible that such defenceless beings as babies should face such serious risks in a product as widely used as milk," Alemanno said in a statement.

Italian officials said they had already seized about 2 million litres of Nestle baby milk earlier this month after finding traces of isopropylthioxanthone (ITX), an ink component used in the offset printing process of the Tetra Pak cartons.

They broadened their net on Tuesday, sweeping hundreds of packets of milk off supermarket shelves and out of depots around Italy. Police said they also searched lorries in their effort to root out the four Nestle products under investigation.

Nestle, the world's biggest food company, said it had decided to recall all liquid infant formula milks packed in offset printed cartons in Italy, France, Spain and Portugal.

"This decision was taken as an extreme precautionary measure to reassure consumers," the company said in a statement. "Nestle believes that the level of ITX measured in the tested products does not represent a health risk."

BOTTOM LINE SAFE

A spokesman at Nestle's corporate headquarters in Switzerland said a new packaging process had been put in place to prevent the contamination and that the recall would not have a significant impact on the company's results at a group level.

Nestle shares were down 0.5 percent at 1615 GMT in a slightly higher overall Swiss market.

Tetra Pak spokeswoman Patricia O'Hayer said ITX was not recognised as a toxic substance on any official list and was not on the World Health Organisation lists of toxic substances that should not come into contact with food.

"We have studied the toxicological data available, and that confirms that it is not toxic," she told Reuters.

O'Hayer said Tetra Pak removed the printing technology in question in October to prevent any printing compound, even if not dangerous, from seeping into a product.

"We had no indication that this was in any way a cause for concern," she said.

This is the second time Nestle has run foul of Italian authorities this year.