A Chinese company at the centre of a contamination scare that has led to a recall of pet foods in North America and Europe said on Friday it had never exported wheat gluten to the United States.

The U.S. Food and Drug Administration (FDA) said wheat gluten from China's Xuzhou Anying Biologic Technology Development Company Ltd. contained an industrial chemical called melamine, which was suspected of causing the deaths of 16 cats and dogs.

But a manager at Xuzhou Anying told Reuters the company was cooperating with the Chinese government to investigate the allegations and insisted the firm was only a domestic feed dealer that had not produced anything itself.

"We haven't sold an ounce of wheat gluten to the U.S. and I don't understand how come they are blaming us," the manager, surnamed Mao, said by telephone.

Anying's company profiles on the Internet describe it as a feed manufacturer and exporter.

China's quarantine authorities said the country was carrying out a nationwide inspection on the quality of its wheat gluten.

"Sampling and examination are under way," the official Xinhua news agency quoted Xia Wenjun, an official at the General Administration of Quality Supervision, Inspection and Quarantine, as saying.

Earlier this week, the administration said that China had never exported wheat or wheat gluten to the United States, a main wheat producer, or to Canada, where Menu Foods is based.

Xia said officials would stay in touch with the U.S. Embassy in Beijing on the results of the inspection but made no comment on Xuzhou Anying.

Menu Foods has recalled a variety of its pet food products in the United States, Canada and Europe.

The FDA had said the suspect wheat gluten had been sold by Anying to ChemNutra Inc. of Las Vegas, which in turn had sold the wheat gluten to Menu Foods and a few other companies that have since recalled pet products.

FDA officials said they were uncertain whether melamine had actually caused the pets to become ill. They said limited studies have found melamine is "fairly nontoxic," but investigators are considering whether dogs and cats might be especially sensitive to it, or whether another chemical may also have been present.

Chinese authorities have also dismissed New York state officials' earlier claim that Chinese gluten might have contained aminopterin, a toxin used in rat poison, and might have caused the pet deaths.