Almost half a billion dollars worth of smuggled frozen meat -- some of it rotting and more than 40 years old -- has been seized in China, reports said Wednesday.

More than 100,000 tonnes of chicken wings, beef and pork worth up to three billion yuan ($483 million) were seized in the nationwide crackdown, the state-run China Daily newspaper said.

"It was smelly, and I nearly threw up when I opened the door," said an official from Hunan province, where 800 tonnes were seized.

Two gangs from the central province were among 14 busted across the country in the operation which concluded earlier this month.

A report on the official Hunan propaganda website said that the meat seized locally came from the "border area" with Vietnam, where it was "difficult to control the flow of meat".

But the China Daily report did not specify the frozen meat's origin and the seizures were not reported on the website of China's General Administration of Customs.

Officials from Guangxi, a southern region bordering Vietnam, found some of the meat was "more than 40 years old", the newspaper said.

That would mean it was originally packed and stored when the country still under the rule of Communist China's founding father Mao Zedong, who died in 1976.

The China Daily said smugglers bought cheap meat abroad, shipped it to Hong Kong and on to Vietnam before bringing it to the mainland.

Yang Bo, deputy director of the anti-smuggling bureau in the Hunanese capital Changsha, said they would often transport the goods in ordinary vehicles, rather than refrigerated ones, to save costs.

"So the meat has often thawed out several times before reaching customers," he added.

Poor food safety is a major concern in China, where standards are lax and scandals involving tainted products are common.

China was rocked by one of its biggest-ever food safety scandals in 2008 when the industrial chemical melamine was found to have been illegally added to dairy products, killing at least six babies and making 300,000 people ill.