Beijing lashed out Tuesday at a US court that ordered two Chinese pharmaceutical companies to pay $162 million for price-fixing in the US market, saying the ruling infringed its sovereignty.

A federal court in New York last week ordered the North China Pharmaceutical Group Corp (NCPC) and one of its affiliates to pay the huge sums after a jury found they had fixed prices on vitamin C exports to the US, Dow Jones Newswires reported.

The case was brought by US firms which alleged that Chinese vitamin C makers formed an illegal price-fixing cartel, increasing prices significantly and costing consumers tens of millions of dollars from 2001.

The jury awarded $54 million in damages, which the judge tripled to $162 million as it was an antitrust violation, Dow Jones reported. It was the first time Chinese companies had faced such court action in the United States.

Shen Danyang, a spokesman for China's Ministry of Commerce, said the Chinese firms were acting in compliance with Chinese laws at the time and branded the ruling as "unfair and improper".

It failed to respect Chinese legislation and Chinese courts' jurisdiction over matters within the country, he added.

"The Chinese companies carried out their actions simply to comply with the compulsory requirements imposed by Chinese government agencies at the time," he told a press conference.

"We hope the US court... fully respects the Chinese government's sovereignty and maintains due international order.

"We will continue to firmly support Chinese companies who comply with the laws, to actively protect their legal rights and interests."

NCPC, one of China's four-largest vitamin and antibiotic suppliers, has said it will appeal the decision, according to China's official Xinhua news agency.