BEIJING (REUTERS/AFP) - Taiwan's government has denounced China, citing entrapment and manipulation, after Chinese state television aired a documentary showing a Taiwanese citizen confessing to visiting Hong Kong to support anti-government protesters there.

China, which claims democratically ruled Taiwan as its own territory, has repeatedly denounced Taipei for offering support to Chinese-administered Hong Kong's protest movement, saying the forces of Taiwan and Hong Kong independence are colluding.

Taiwan says it has a duty to stand up for democracy and human rights.

Lee Meng-chu who is currently detained in China and accused of "endangering national security" appeared on Chinese television on Sunday (Oct 11) evening, admitting to illegally filming military exercises in a city bordering Hong Kong during protests there last year.

Relatives of Lee Meng-chu had said he went missing after crossing from Hong Kong into Shenzhen on Aug 19, 2019.

Hong Kong was then in the throes of months-long mass demonstrations against a law allowing extradition to China, the territory's government and the central government in Beijing.

At the time, thousands of Chinese military police had gathered in a stadium in Shenzhen for exercises with armoured vehicles.

The manoeuvres had fuelled speculation that China was going to deploy its forces to intervene in the Hong Kong unrest.

"I took my phone to record some videos," Lee said in the CCTV state television report on Sunday, interspersed with scenes from his alleged actions.

"I am sorry. I have done a lot of bad things," said Lee, his hair cropped short, wearing a blue shirt and an orange vest with his prisoner number.

According to CCTV, he went to Shenzhen for the sole purpose of observing the manoeuvres.

He reportedly shot 16 videos and took 48 photos around the stadium. After he shared some on the internet, he was reportedly arrested by state security.

In Taipei, the Mainland Affairs Council labelled the show "complete nonsense".

"This is malicious political hyping up by the other side, entrapping one of our people into engaging in spying activities, deliberately damaging relations across the Taiwan Strait," it said.

China should stop trying to frame Taiwanese citizens, the council added, saying putting Lee on television was contrary to the legal process.

Rights groups and Western governments have expressed anger at China for previous instances where suspects have been put on state television to confess before their trials.

The spying accusations come as relations between Taipei and Beijing continue to nosedive, with China stepping up military drills near the island in recent weeks.

Taiwan says it will not provoke China or seek war, but that it will defend itself and stand up for its democratic way of life.