Authorities in a northeastern Chinese city on Wednesday vowed severe punishment for those responsible for melamine-contaminated eggs turning up in Hong Kong as the health scare spread to another city in eastern China.

At least four children have died and tens of thousands were made ill amid the melamine scandal, the latest in a series of health scares to sully the "made in China" label.

Chinese products ranging from chocolate to milk powder have been recalled throughout the world due to contamination fears. Melamine — used in making plastic chairs, among other things — is often added to cheat nutrition tests.

Chinese eggs are now in the spotlight after Hong Kong food safety authorities over the weekend found melamine-contaminated eggs produced by Hanwei Group in the northeastern port city of Dalian on local shelves.

Problem eggs have now been found in Hangzhou, capital of the eastern province of Zhejiang, the official Xinhua news agency said on Wednesday, citing quality authorities there who had ordered a city-wide recall of all Ciyunxiang brand eggs.

The tested batch of Ciyunxiang eggs, produced by Green Living Beings Development Centre based in China's northern Shanxi province, contained 3.5 milligrams of melamine in every kilogram, Xinhua said. Calls to the company went unanswered.

China currently has no standard for acceptable amounts of melamine in eggs, but allows only 2.5 mg per kilo in most milk products.

There had been no reports of people being made ill from the eggs in Hangzhou, Xinhua said, but the government-led recall — the first for eggs in China — suggests the problem may be widespread and could usher in a round of checks nationwide.

Authorities in Dalian on Wednesday blamed tainted chicken feed for the high levels of melamine found in Hanwei Group eggs exported to Hong Kong. The municipal government promised harsh punishment in a notice posted on its website.

Hanwei apologized to consumers and distributors on Tuesday. Its chairman, Han Wei, said the company had never bought melamine, or added the compound to feed or products. Han is a member of the Chinese People's Political Consultative Conference, an advisory body to parliament, and has been a leading advocate of food safety in China.

It was not immediately clear how the Hanwei eggs passed tests, if any, in Dalian. Chinese officials this month said the melamine health scare was over.

Hong Kong said it had also detected melamine in a batch of eggs from China's central Hubei province on Tuesday. China supplies up to 60 per cent of the eggs consumed in the former British colony, which returned to Chinese rule in 1997.

Wal-Mart pulls eggs in China

Wal-Mart Stores Inc. pulled Gegeda-brand eggs, which are produced by Hanwei, from its stores in China on Tuesday. Company public relations official Vivi Mou said the move was voluntary and eggs of other brands were still on the shelf.

The health scare involving eggs comes as hundreds of parents across the country attempt to sue the Sanlu dairy group, where the scandal first broke in mid-September with tainted baby formula.

None of the lawsuits have been admitted by any court so far.

With files from Reuters