A 31-year-old man is recovering in a Hong Kong hospital after being released by kidnappers, a report in the South China Morning Post said.

The man - believed to be the grandson of Hong Kong tycoon Li Po-chun - was released after his family paid a ransom, thought to be US $10m.

Acting chief superintendent Lo Mung-hung of the Organised Crime and Triad Bureau has refused to confirm or deny the case.

The victim's release came after kidnapped 80-year old businessman So Chak-tong was rescued earlier this week.

Local journalists say kidnap has become an increasing threat for businessmen there.

Business threat

"It has become increasingly frequent and it affects the very most prominent people in Hong Kong," Stephen Vines in Hong Kong said.

"Prominent business men here very obviously do have security guards."

"Nowadays, if you want to be known as someone who is important in town, you need to have a body guard...this one seems to have become a prestige thing as well," he said.

The kidnappings are often attributed to triad gangs, who are thought to carry them out - if not necessarily instigate them.

Outside of Hong Kong, reports suggest that kidnapping of company employees is becoming a lucrative business for guerrilla and criminal groups around the world.

According to the London-based political think-tank The Foreign Policy Centre (FPC), economic kidnapping is one of the fastest-growing industries in the world.