Spain-based rights group Safeguard Defenders said the figure for what they call "involuntary returns" could just be the "tip of the iceberg".

The report states that China president Xi Jinping's government has been aggressively pursuing its overseas nationals as it targets people wanted as part of its anti-corruption drive.

The group alleges that China's ruling Chinese Communist Party (CCP) has been using illegal means such as harassing, intimidating or detaining relatives in order to coerce nationals to return from over 120 countries.

"With the Chinese diaspora growing at an ever faster rate as more people seek to leave China, and with the CCP keen to keep control of them also, Beijing has never been more motivated to expand the powers of its security forces overseas," the report said.

Through two programmes, Operation Fox Hunt and Operation Sky Net, targeted individuals were pressured to return to China against their will through a combination of non-judicial methods, including kidnappings, harassment and intimidation, according to the report.

Safeguard Defenders cited government data in its estimate that almost 10,000 Chinese nationals had been forcibly returned since 2014.

The reports details the case of tycoon Xiao Jianhua, who is a Canadian citizen, and was allegedly abducted by Chinese agents from his hotel room in Hong Kong in 2017.

CCTV cameras show him being pushed out of the hotel in a wheelchair with his head covered by a blanket.

He has not been seen since but reports say he was taken back to the mainland to help with police investigations.

China has previously been accused of carrying out kidnappings abroad.

What is an involuntary return?

Safeguard Defenders defines this as "the use of non-traditional, often illegal, means of forcing someone to return to China against their will, most often to face certain imprisonment.

"Methods range from threatening family back in China, sending agents to intimidate target in host country, to direct kidnappings," the organisation added.