The legal limit for melamine in food products in Hong Kong is 2.5 ppm.

The Hong Kong Special Administrative Region's (SAR) Secretary for Food and Health York Chow said melamine might have come from the feed given to the chickens.

"The initial opinion of experts is that there is a problem with the (chicken) feed," Chow said on Saturday.

A day later, he said results of the tests on eggs have prompted officials to expand the tests to mainland meat products.

Hong Kong officials will step up tests on eggs imported from the mainland, too.

Calls to Dalian Hanwei Enterprise Group, based in Liaoning's port city Dalian, went unanswered on Sunday.

Before the egg scandal, melamine was found in baby milk food.

More than 3,600 children are still suffering from numerous urinary ailments, including kidney stones.

Altogether 60,000 infants fell victim to contaminated milk food, and four succumbed to their illness.

The SAR government said it also found excessive amounts of melamine in Blueberry Cream Sandwich crackers made by Philippine company Croley Foods MFG Corp.