ZURICH/JOHANNESBURG (Reuters) - Nestle, the world's largest food company, has recalled infant formula manufactured in South Africa after a mixing error led it to contain excessive levels of copper, iron and zinc.

The company recalled the entire batch after 250 tins were discovered to have contained raised levels of trace metals and is investigating the cause of the contamination.

"We have received 15 customer complaints since our announcement yesterday ... We have been told that the babies have been vomiting or having diarrhoea," Theo Mxakwe, spokesman for Nestle South Africa, told Reuters.

"The process (of recalling) started last night and is still continuing today."

Nestle Switzerland said the product could make children sick if consumed but was so unpleasant looking and smelly it was highly unlikely that any child would actually swallow it.

"The problem with the product is that once it is reconstituted, it may change colour, have a rancid smell and separate," said spokesman Robin Tickle.

"The likelihood of the child consuming it in terms of bringing it down and keeping it down is very small. But we cannot exclude negative health affects if you consume it."

The recall affects Lactogen 1,400 gram tins with a batch code 73100179 L1, manufactured on November 6 and distributed in South Africa, Botswana and Zambia.