China's state news agency Xinhua reports that Gui, 51, was convicted of drunk driving in August 2004.

He was reportedly sentenced to two years in prison, which was deferred for two years, after he struck and killed a female college student.

Xinhua alleges that, fearing prison, he went on the run in 2004. Chinese police have purportedly been looking for him since, although according to Leung Chun-ying, Hong Kong's chief executive, his case was never referred to Hong Kong police.

"The Gui Minhai case has not been reported to the Hong Kong Police or the Hong Kong Government," he told journalists. "We attach a great deal of importance to such and any other information that could help the Hong Kong Police and the Hong Kong Government to understand the case better."

Police walk past missing person notices of Gui Minhai (L) and Yau Wentian (R)

Gui Minhai's sudden desire to return to China was said to have been driven by the news that his father had passed away and a wish to spend time with his elderly mother.

"Going back to my country and turning myself in was voluntary. This was not related to others," he told Chinese state television CCTV in an interview.

"I must take legal responsibility for my own actions, and I am willing to accept any punishment," he said on camera.

"Although I now hold Swedish citizenship, deep down I think of myself as Chinese. I hope the Swedish authorities will respect my personal choices, my rights and privacy, and allow myself to deal with my own issues."

Swedish officials declined to comment on the latest developments.

"We are aware of the information published in news media," a representative from the Swedish Embassy in Beijing told CNN.

"We continue to seek clarifications from the Chinese authorities."

Crackdown?

A recent spate of arrests of human rights lawyers and activists in China has created cause for diplomatic concern and incurred widespread condemnation from human rights groups.

Last week a Swedish human rights activist was detained in China. Swedish officials told CNN they had visited the detainee and "he was feeling well, considering the circumstances."

As well as Gui Minhai, four other Hong Kong booksellers have also disappeared, triggering street protests and stoking concerns of Beijing's governmental encroachment despite the city's autonomy, guaranteed under a joint Sino-British agreement, signed in 1984.

The latest person connected to the publishing house to vanish, Lee Bo, disappeared last month.

"Gui's reappearance in Chinese custody reinforces concerns about the fate of his other associates," said Nicholas Bequelin, East Asia Director at Amnesty International.

"We can't exclude that Gui Minhai's videotaped 'confession' wasn't made under duress. We want to ensure he has access to a lawyer, as mandated under Chinese law."

He also raised that the CCTV segment did not seem to address the sequence of events that led Gui from Thailand to custody in China.