The demonstrations highlighted the years-long struggle among former soldiers of the world's biggest standing army to get better benefits, posing a headache for the country's Communist leadership.

Authorities in China have little tolerance for public dissent but the People's Liberation Army and its veterans are venerated as heroes, and protests continued for days in the city of Zhenjiang before police intervened on Sunday.

"Scores of armed police came yesterday along with government officials to force everyone to go home. Some people were detained and we're not sure about their whereabouts," a witness who supported the veterans told AFP.

Thousands of army veterans have staged protests in recent years against officials whom they accuse of denying them benefits.

Witnesses said hundreds of veterans came to Zhenjiang from across the country after unconfirmed reports that security guards had beaten a group of elderly veterans outside a municipal building earlier this month.

"They were very well organised with tents and provisions, and every day, people from Zhenjiang came to join and support them," a local schoolteacher told AFP, also requesting anonymity out of safety concerns.

The witness recorded a video showing about 100 protesters outside a hospital where at least one beaten pensioner was believed to be recuperating.

Another witness video showed soldiers marching with red banners declaring: "We are Communists, not criminals."

Footage from the protests appeared to be censored on China's popular Weibo social media website but unverified clips appeared on Twitter, which is blocked in the country.

Several veterans contacted by AFP said they were "unable to speak about the situation".

A veteran who was not present at the protests said he has "lost contact" with friends who demonstrated and feared violence may have been used to expel them.

The government had prevented other retired soldiers from travelling to Zhenjiang, he added.

China's defence ministry had vowed in 2016 to improve living standards for veterans after thousands had demonstrated outside army offices in Beijing.

China has laid off more than a million troops since the 1980s and vowed last year to further cut its two-million strong army.

Many former soldiers, with little formal education, have found it difficult to re-adjust to normal society and find jobs in the civilian economy.

The Ministry of Veteran Affairs opened in April with the aim of streamlining pensions and retirement benefits, which vary widely in the country.