Tests over the weekend detected melamine in eggs imported from Dalian in northeastern China at levels that were nearly twice the legal limit, further blighting the 'made in China' label, according to Yahoo.

"We have contacted the mainland's food safety agency and hope they can do more to reduce the risk at the source," Health Secretary York Chow was reported as saying by local newspapers.

Tends of thousands of Chinese infants have fallen ill with kidney problems after consuming milk that had been mixed with the plastic-making industrial chemical to cheat quality tests. Four children died.

With weeks, tests found melamine in a variety of Chinese-made products from milk and chocolate bars to yoghurt exported around the world, including egg products in South Korea, leading to items being pulled from shop shelves.

Premier Wen Jiabao, at the closing of an Asia-Europe summit on Saturday, vowed China would do all it could to bring the quality of Chinese food products up to international standard.

But it has emerged that cyromazine, a derivative of melamine, is widely used in pesticides and animal feed in China, and experts say it is absorbed in plants as melamine and that the chemical is already in the human food chain.

However, no one knows how much melamine is absorbed into raw foods such as meat and vegetables, and experts are hoping Hong Kong's tests on vegetables and meat will shed some light.

"Since some animal feed used on the mainland might have been polluted by melamine, our tests will target more on meat imported from the mainland," Chow was quoted as saying.

"As we have found melamine in eggs, we shall also test chicken meat and we shall also look at offal, for example chicken kidneys and pig kidneys."

Hong Kong said last week it would test meat, vegetables and processed food for melamine, a move that underlines concerns about food safety in the former British colony which returned to Chinese rule in 1997.

It imposed a cap on melamine in September, restricting it to no more than 2.5 milligrams per kilogram, while melamine found in food meant for children under three and lactating mothers should be no higher than one mg per kg.

The level of melamine found in the eggs was 4.7 mg per kg, the newspapers said.

China has been swept by a series of food- and product-safety scandals involving goods as diverse as toys, tires, toothpaste, pet food, fish, beans, dumplings and baby cribs.

The Yahoo report says that Wal-Mart Stores Inc said on Wednesday it planned to crack down on its Chinese suppliers, enforcing stricter quality and environmental standards.