TAIPEI (AFP) - Taiwanese police have rescued a kidnapped Hong Kong tycoon who was held hostage for more than a month and beaten up by a gang demanding a US$9 million (S$13 million) ransom, authorities said Wednesday (Oct 28).

Wong Yuk-kwan, chairman of the Hong Kong-listed Pearl Oriental Oil exploration company, was found manacled Tuesday in a shack in a western Taiwan village after being abducted outside Taipei on Sept 20, according to authorities.

Television footage of the rescue showed the 67-year-old, also known as Wong Kwan, looking thin and frightened as he sat on the floor of a bare room with his feet shackled.

His face was bruised and he was clutching his legs, which were covered in cuts.

Fifteen people were arrested over the abduction including the suspected mastermind.

In emails to Wong's office in Hong Kong the kidnappers had demanded a ransom of HK$70 million (S$13 million), to be paid in virtual currency bitcoins.

An official from New Taipei City police told AFP no ransom was paid. Taiwanese police were assisting Hong Kong officers with their investigations into the case.

Wong's company, in a statement to the Hong Kong stock exchange, said it was contacted by him on Wednesday.

"Wong confirmed he had been kidnapped since 20 September in Taiwan until the night of 27 October, when he was successfully rescued by Taiwan police," the statement said.

Even though he was undergoing a physical examination, the chairman was able to resume his role with the company with "immediate effect".

The businessman, who was visiting Taipei for medical treatment according to media reports, is still facing charges that were brought against him and Pearl Oriental Oil executives in 2013 by Hong Kong's anti-corruption watchdog.

He is accused along with three others of fraud and money-laundering relating to the acquisition of an oilfield in the United States.

He has been free on HK$5 million bail since then.

Two of the defendants in the case were found guilty in May and sentenced to seven years and five years in jail respectively.

Pearl Oriental Oil's main business is oil and gas exploration and the company is valued at HK$957 million. Its main asset is an oilfield in Utah and it also runs a plastic recycling business, according to its website.

Hong Kong has a long history of kidnaps targeting high-profile members of the business community.

In April a Hong Kong textiles heiress was abducted and released three days later after her family paid her captors a ransom of HK$28 million.

Nine people were arrested over the abduction after Hong Kong authorities launched a massive hunt.