A Taiwanese democracy activist jailed in China for five years returned home on Friday after serving his full sentence in a case that had strained relations between the two neighbours.

Local media live-streamed footage of Lee Ming-che's arrival in Taiwan via a Xiamen Air flight before he was escorted by two airport workers in pandemic protection suits into a car.

Lee was jailed by a court in central China in November 2017 on charges of subverting state power.

He was arrested in March that year during a trip to the mainland and held incommunicado for months before his fate was revealed.

Taiwan's government called Lee's imprisonment "unacceptable" and a serious blow to relations with Beijing, while his wife Lee Ching-yu described his trial as a "political show".

The activist on Friday expressed gratitude to people who had pushed for his release and voiced concern over human rights violations in China.

"My family's suffering is over but we don't know how many people there are in China whose human rights have been violated. I hope they will find relief one day," he said in a Facebook post.

"Freedom is earned by oneself... May the Chinese people realise and learn this. Bless the Chinese people."

A coalition of Taiwanese NGOs that had campaigned for his release published a statement after Lee's return.

"We have maintained all this time that Lee is innocent as he only made comments on the internet about human rights and civil society in China," the statement read.

Lee Ching-yu said in a Facebook post on Thursday that she had only learned about her husband's release from media reports.

She said they were planning to hold a press conference after Lee finishes a period of mandatory Covid quarantine.

She was temporarily banned from visiting her husband after criticising prison conditions, citing a notice from authorities that accused her of a "serious distortion of the facts".

Her husband had lost weight because food was often rotten and he was denied warm clothing and had to work over 10 hours daily, she had said.

During his trial, Lee pleaded guilty, stating that he had written and distributed articles online that criticised China's ruling Communist Party and promoted democracy.

He had shared "Taiwan's democratic experiences" with his Chinese friends online over many years and often mailed books to them, according to the Taiwan Association for Human Rights.

Under President Xi Jinping, China has become even less tolerant of dissent and activism.

Lee's arrest also came at a time when relations between Beijing and Taipei were plunging.

China ramped up economic, military and diplomatic pressure after the 2016 election of President Tsai Ing-wen, who views the island as an already sovereign state.

Beijing claims Taiwan as its territory and has vowed to one day seize it.

But the majority of Taiwanese do not want Chinese rule and in 2020 Tsai won re-election in a landslide.

AFP