Fast food has become increasingly popular in India

In North America, the fries are first cooked at plants using beef fat, and then frozen before being shipped to the restaurants for further frying.

American Hindus have started legal action seeking damages, which they say could run to millions of dollars.

In India the revelation caused rioting until the company assured local people that the method of cooking there was strictly vegetarian.

McDonald's has nearly 30 restaurants in India, selling chicken, lamb and vegetarian products

Apology

McDonald's has now conceded ground. The corporation's website on nutrition says it regrets if customers felt information was incomplete.

McDonald's fries are world famous

A spokesman for McDonald's said: "We're not too big to apologise."

The company has also clarified its policy, saying that in predominantly Muslim countries it conforms strictly to Halal standards with no beef or pork flavouring.

But the apology is unlikely to head off the lawsuit in the United States being brought by the Hindus, for whom the cow is a sacred animal.

In America, non-Hindu vegetarians are divided on the issue.

Some say they are outraged, but others say that the name McDonald's is synonymous with beef - so what did customers really expect?