Chinese authorities have discovered 157 dead pigs in a river, according to state media, raising concerns over food safety one year after 16,000 carcasses were found in a river in Shanghai.

The dead animals were found in the Gan river in Jiangxi, which according to the news agency Xinhua, supplies drinking water to Nanchang city.

The river is a tributary of the Yangtze, one of China's main waterways.

Tests carried out by Nanchang officials have confirmed the tapwater is still safe to drink.

It was originally reported that 131 pigs were recovered from the river. However, the state broadcaster CCTV confirmed later on Sina Weibo, a Chinese version of Twitter, that more had been discovered, saying: "Another 20 pigs have been fished out of the Gan River, for a total of 157."

The origin of the pigs remains a mystery, yet ear tags indicate the animals came from Zhangshu, which is part of Yichun city in the central Chinese Province. Photographs posted by CCTV showed authorities in face masks and white overalls examining carcasses lined up on a river bank.

In early March 2013, over 16,000 dead pigs were found along sections of the Huangpu river in what became a major food safety scandal.

The Huangpu river snakes through Shanghai, providing the city with some of its drinking water.

No official explanation for the emergence of the pigs was provided, yet it is suggested the animals were dumped by farmers in Jianxing in the Zhejiang province.

A report on Xinhua News Agency alleged that intensive farming was the probable cause of the animals.

The BBC reported that some of the corpses tested positive for porcine circovirus, a common pig virus.

This month, Premier Li Keqiang met with New Zealand Prime Minister John Key at the Great Hall of the People in Beijing, China, to discuss the safety of New Zealand food products after last year's global botulism scare.

In August 2013, the New Zealand dairy company Fonterra was forced to recall products, including infant formula, over a suspected contamination with Clostridium botulinum.

The bacterium Clostridium botulinum can cause botulism, a potentially fatal disease that affects the muscles and can cause respiratory problems.

Baby milk formula has become a hugely sensitive topic, along with food safety, after the 2008 milk scandal which affected 300,000 people and led to six infant deaths.

The 2008 scandal exploded after it was found that milk and infant formulas had been laced with melamine, which appeared to have been added to the milk to cause it to appear to have a higher protein content.

In his address to China's parliament this month, Li Keqiang pledged to "apply the strictest possible oversight, punishment and accountability to prevent and control food contamination and ensure that every bite of food we eat is safe".