HONG KONG (REUTERS) - One of Hong Kong's staunchest pro-Beijing lawmakers said a bookseller's tearful confession on state television to a hit-and-run accident more than a decade ago in China is unlikely to appease public concerns that he may have been abducted.

The Sunday evening broadcast on China Central Television ended months of mystery over the fate of Mr Gui Minhai, a naturalised Swedish citizen, after he was last seen in October outside his apartment in the Thai seaside town of Pattaya.

In the strongest statement yet by anyone in Hong Kong's pro-China camp, Legislative Council president Jasper Tsang said the taped confession by Mr Gui was not enough.

"The China Central Television (CCTV) report did not seem to be able to calm the public. As the case drags on, there will be more speculation," Mr Tsang said late on Monday (Jan 18).

He said if more details did not come to light, the Hong Kong government should seek assistance from the central government in Beijing.

CCTV could not be reached for comment.

Since late last year, four other associates of the Hong Kong-based publisher that specialises in selling and publishing gossipy political books on China's Communist Party leaders have been unaccounted for.

Hong Kong police confirmed late on Monday that they had been advised by the authorities in China's southern Guangdong province that one of them, British passport holder Lee Bo, was in the mainland.

Police said Guangdong officials also sent them a letter from Mr Lee addressed to the Hong Kong government, and that Mr Lee's wife confirmed the writing was his.

Police said it was similar to one he purportedly sent to his wife in which he said he "voluntarily" went to the mainland.

The disappearances have prompted fears that the mainland Chinese authorities may be using shadowy tactics that erode the "one country, two systems" formula under which Hong Kong has been governed since its return to China from British rule in 1997.

"We should not speculate and criticisms should be based on fact," Hong Kong leader Leung Chun Ying said on Tuesday. "I and SAR government are also very concerned about the case."

Chinese Foreign Ministry spokesman Hong Lei said on Tuesday that he had nothing more to add about Mr Gui's case as the Chinese media had already given a "rather detailed" report on his case.

On Mr Lee's case, he said he "did not understand" it.

Hong Kong was returned to China with a guarantee that it would have greater freedoms and separate laws from the mainland for 50 years.

The publishers' books are banned on the mainland, although they are popular with Chinese tourists in Hong Kong.

"We will continue to raise this case at the highest levels,"a British Foreign and Commonwealth Office's spokesperson said in an email response to Reuters, referring to Mr Lee.

Sweden and the United States have also expressed concern at the disappearances.

Some observers, including journalists and commentators, highlighted on social media what they believed were discrepancies in the state media reports on Mr Gui, including what appeared to be changes in the colour of his undershirt in the course of the CCTV footage.

Mr Gui's daughter Angela said the Swedish authorities had told her there was no record of her father leaving Thailand, and that staff at his condominium said he had just returned from grocery shopping when he went missing.

"I still think he was abducted," said Ms Gui, 21, in a telephone interview from Britain, where she is studying.