BEIJING -- More than 1,000 protesters walked and chanted in front of China's defence ministry Tuesday, the latest apparent demonstration by soldiers as the world's largest standing military modernizes and downsizes.

The protesters stood for several hours in front of the Bayi building in central Beijing, home of the Chinese Ministry of National Defence. Many wore green fatigues bearing the hammer-and-sickle logo of China's ruling Communist Party.

The purpose of their demonstration was unclear. Protesters approached by The Associated Press declined to be interviewed, and censors blocked searches on social media about retired soldiers or the Chinese defence ministry.

Hundreds of police and plainclothes security officers surrounded the protesters, hemming them in with buses and police vehicles.

While Chinese authorities routinely suppress discussions about the military and soldiers' issues, one human-rights activist, Huang Qi, told the AP that veterans have staged more than 50 protests this year alone. However, demonstrations on such a large scale are extremely rare in the centre of the heavily policed capital.

Two demonstrators told AP they were veterans who wanted the government to address military pensions, but they didn't want to discuss the issue with foreign media. The protesters declined to give their names.

Liu Feiyue, editor of the website Minsheng Guancha, which monitors civil rights issues, said he was told by retired soldiers that other ex-soldiers were present.

"They protested because they don't have a job now after serving a long period of time in the army, some for a dozen years," Liu said. "They are asking for employment."

China's armed forces are undergoing a large-scale modernization to become a nimble organization that can better handle conflicts at sea and in the air.

Those measures have gained pace as China builds up its presence in the South China and East China Seas amid territorial disputes and as relations have soured with self-governing Taiwan -- which China claims as its own territory to be unified with by force if necessary.

President Xi Jinping announced last year that the 2.3-million-member People's Liberation Army would cut 300,000 personnel but little has been said about the cost or where the surplus troops would go.

Veterans have staged sit-ins and protests for several years over low or absent pensions and an inability to find work outside the military.

It wasn't clear if anyone had been arrested Tuesday. Local police did not respond to faxed questions, and no one answered the phone at the press office of the defence ministry.