Thousands of people took to the streets of a city in eastern China to protest against a possible Sino-French nuclear project, residents said on Monday, as local police denied beating demonstrators.

Residents in Lianyungang, 480 kilometres (300 miles) north of Shanghai, shouted slogans and waved banners outside government offices at the weekend to complain about the health impacts of a suggested nuclear waste processing plant.

"There were several thousand people," a hotel worker who declined to be named told AFP by telephone. Another local surnamed Xu described "clashes between police and protesters".

French nuclear fuel group Areva in 2012 agreed to cooperate with state-run China National Nuclear Corp (CNNC) to build a reprocessing facility in China, without stating the location.

Locals say that Lianyungang, a port city in Jiangsu province, is a prime candidate, because a large new nuclear power station is being built by CNNC nearby.

"Building a nuclear waste processing plant in Lianyungang is a recipe for disaster for future generations, local people have a right to express anger," a male hotel worker who declined to be named said.

Pictures posted online showed locals massing in a public square surrounded by hundreds of police.

The city's police on a verified social media account Monday denied a "rumour" that they had beaten protesters resulting in the death of one person.

The protests highlight local opposition to nuclear projects in China, which is increasing its nuclear power capacity on a huge scale and encouraging state-run firms to build plants abroad.

Mainland China has 34 nuclear power reactors in operation, 20 under construction, and work about to start on more, according to the World Nuclear Association.

Safety fears grew following a series of meltdowns at Japan's Fukushima nuclear power plant in March 2011 that were intensely covered by China's state-run media.

China's environmental ministry said in a report the same year that the country's nuclear safety situation was "not optimistic", and that the use of differing types of reactors in Chinese plants made the sector "difficult to manage".