A murder suspect whose case sparked Hong Kong's ongoing protests has been freed from prison, telling reporters he was willing to stand trial in Taiwan, where he is wanted for killing his girlfriend.

Key points: Hong Kong citizen Chan Tong-kai is accused of killing his girlfriend in Taiwan, but was jailed for money laundering

Hong Kong citizen Chan Tong-kai is accused of killing his girlfriend in Taiwan, but was jailed for money laundering The protests started after an extradition bill was proposed that would allow suspects to be sent from Hong Kong to greater China

The protests started after an extradition bill was proposed that would allow suspects to be sent from Hong Kong to greater China Hong Kong and Taiwan cannot agree whether Chan can travel by himself or if he should be accompanied by authorities

Chan Tong-kai, a Hong Kong citizen, was accused of murdering Poon Hiu-wing in Taiwan last year before fleeing back to the Chinese-ruled financial hub.

The case was the jumping-off point for the mass street protests in Hong Kong, which have now evolved into a broader pro-democracy movement.

Chan bowed and apologised to Ms Poon's family and the public as he left the prison in Hong Kong's rural Sai Kung district after serving 29 months for money-laundering offences.

He said he had made an "unforgivable mistake".

"I am willing, for my impulsive actions and things I did wrong, to surrender myself, to return to Taiwan to face sentencing and stand trial," he said, but declined to say when he would hand himself over to Taiwanese authorities.

He got into a van and reporters gave chase, broadcasting live as the van made its way to an upscale gated apartment complex that they could not enter.

While Chan has offered to surrender himself voluntarily, Hong Kong and Taiwan have clashed over the next steps.

Embattled Hong Kong leader Carrie Lam held up Chan's case as an example of why an extradition bill was needed — such a bill would have allowed suspects to be sent from Hong Kong to greater China, including the mainland, Taiwan and Macau.

The former British colony has been reeling from five months of unrest originally triggered by the proposed extradition bill.

Taiwan, Hong Kong squabble over Chan's handover

The Government announced last month it would withdraw the bill, and the city's legislature formally withdrew the planned legislation on Wednesday.

Hong Kong authorities said Chan should be free to go to Taiwan and surrender himself, but Taiwan's Mainland Affairs Council said in a statement it was "unbelievable" Chan could be expected to take a flight to Taiwan alone, "completely ignoring the safety of passengers on the same flights in order to serve the political arrangement of a 'surrender'".

Chan Tong-kai pledged to surrender himself to Taiwanese authorities but did not say when. ( AP: Mark Schiefelbein )

It said Taiwan had repeatedly asked for legal cooperation.

"We are solemnly telling the Hong Kong Government that you have to take full responsibility for all bitter consequences," the statement said.

Taiwan has also said it wanted to send officers to Hong Kong to escort Chan back to the self-ruled island upon his release, a move the Hong Kong Government has described as a disrespectful and unacceptable attempt to cross legal jurisdictions.

Chan was arrested by Hong Kong police in March 2018 and authorities there were only able to find evidence against him for money laundering.

Ms Lam reluctantly agreed to withdraw the extradition bill two-and-a-half months after anti-government protests escalated in June, although its formal withdrawal is unlikely to end the unrest.

Protesters are angry about what they see as Beijing encroaching on Hong Kong's "one country, two systems", formula enshrined during the handover from British to Chinese rule in 1997.

That formula allows the city wide-ranging freedoms not available on the mainland, such as an independent judiciary.

The extradition bill was seen as the latest move by Beijing to erode those freedoms, but China denied such claims and accused foreign countries of fomenting trouble.

Opponents to the bill fear dissidents could be netted on trumped-up charges and harbour a deep distrust of the ability of Chinese courts to ensure a fair trial.

Reuters/AP