BEIJING - China is carrying out a nationwide inspection on the quality of its wheat gluten after the United States claimed that the pet food at the origin of a number of cat and dog deaths used tainted wheat imported from China.

A dog helps his owner carry a grocery basket Thursday Feb. 12, 2007, in Shanghai, China. [AP]

"Sampling and examination are under way," Xia Wenjun, an official with the press office of the General Administration of Quality Supervision, Inspection and Quarantine, told Xinhua on Friday.

The probing targets melamine, a chemical used to make plastic and discovered by the US Food and Drug Administration (FDA) in the pet food recalled by Ontario-based pet food maker Menu Foods following a rash of animal sickness and deaths.

"We will announce the results as soon as the investigation is completed," Xia said.

The administration in charge of quality inspection and quarantine of imports and exports carried out tests Monday targeting aminopterin, a rat poison previously suspected of causing the deaths but later cleared by FDA tests.

Xia said that the administration would stay in touch with the US Embassy to China and take further measures based on developments in the United States.

She made no comment on Xuzhou Anying Biologic Technology Development Co. which was identified by the US government as the supplier of contaminated gluten.

The company situated in eastern China's Jiangsu Province insisted they had never exported wheat gluten to the United States.

All imports traced to Xuzhou Anying will be held in custody at US customs until investigations are completed, according to the FDA.

Menu Foods commenced a North American recall in mid-March after an unknown number of cats and dogs suffered kidney failure and some died after eating their contaminated pet food.