Chinese customs officials have seized 3 billion yuan ($483 million) worth of smuggled frozen meat, some of which was rotten and over four decades old, in a crackdown on Wednesday.

The meat, including frozen chicken wings, beef and pork, was intended for restaurants, retailers and supermarkets in China's Hunan province, where the batch was seized as well as other Chinese provinces and major cities, according to CNN.

Chinese authorities have launched an operation against beef and frozen meat trafficking in a bid to eradicate the smuggling of farm products in the country. Officials busted 21 criminal gangs by June, seizing contraband of more than 100,000 tons, according to Reuters.

Some packages were rotten, whereas others traced back to the 1970s - packed and stamped at the height of China's Cultural Revolution.

"It was smelly, and I nearly threw up when I opened the door," administration official Zhang Tao said, China Daily reported. 

Thousands of tons of beef are being smuggled into China via Hong Kong and Vietnam from countries like India and Brazil in order to bypass Beijing's import restrictions.

Meat can be preserved for long durations as long as it is frozen, but smuggled meat is usually kept in poor storage conditions, which can cause thawing, and the meat eventually begins to rot.

"To save costs, smugglers often hire ordinary vehicles instead of refrigerated ones. So the meat has often thawed out several times before reaching customers," said Yang Bo, an anti-smuggling official in Changsha.