China's food safety watchdog Friday passed McDonald's chicken McNuggets as safe for human consumption, saying a petrol-based chemical additive in the fast food was within legal limits.

Sample tests showed the amount of tertiary butylhydroquinone (TBHQ) in McDonald's Chinese McNuggets was within the national food additive limit of 200mg/kg, the State Food and Drug Administration said.

Tests were conducted on 35 McNuggets and 33 portions of oil used to fry the food taken from 22 McDonald's outlets in Beijing, Shanghai, Liaoning Province and Guangxi Zhuang Autonomous Region, said a report on the administration's website.

The tests were carried out in response to reports that McNuggets sold in the United States contained dimethylpolysiloxane, an anti-foaming agent, and TBHQ.

Experts said the additives could cause nausea and vomiting if eaten in excessive quantities.

The administration report gave no results of tests for dimethylpolysiloxane as China has not yet published national standards on the additive.

However, the report said food standards authorities were considering it.

The State Food and Drug Administration urged food companies to only use food additives in accordance with laws and regulations in the report so as to ensure "safe" products for consumers.