The men, illegal immigrants from China, were being held at a house in west London by gangsters demanding a pounds 100,000 ransom.
They were abducted nine days ago and their relatives in China were ordered to pay pounds 20,000 a head or the captives would be mutilated and murdered. The criminals telephoned the victims' families in China and forced them to listen to screams of pain as they tortured and beat their hostages.
The kidnap plot is believed to be part of a feud between rival Chinese criminal gangs. The police operation, which led to the arrest of 50 people in London, Essex and Kent, was one of the largest against Chinese gangsters in Britain and is at least the second to involve hostage taking.
The operation also shed light on the scale and diversity of Chinese gang activity in the United Kingdom. The five hostages are understood to have been smuggled into Britain as part of an illegal immigration racket by one Chinese gang and then hi-jacked by a rival outfit.
The suspects, male and female, were arrested in a series of armed raids involving about 200 police officers starting at midnight on Sunday.
The hostages, aged in their twenties and thirties, were released after armed officers from the Metropolitan Police's Organised Crime Group raided a property in Acton.
The officers discovered the five men tied up on the floor. They were described as being in an appalling condition, one had been stabbed in the leg and the others all needed hospital treatment for injuries from the beatings. Eight suspects were arrested at that address.
Detectives from Scotland Yard travelled to China last week as part of the international operation. A Chinese man was arrested in south-east China as he attempted to collect the ransom.
Scotland Yard was alerted by their colleagues in China after families reported the ransom demands for 250,000 Yen (about pounds 20,000 per person). This followed the seizure of four illegal immigrant men who were hijacked by Chinese criminals from the house they were staying and marched into four cars and taken to their hideout in west London. It is not known where the fifth man was kidnapped.
Officers from the Metropolitan Police, assisted by the Kent and Essex forces, took part in Sunday's raids. Suspects were also arrested at four addresses in Essex and two in Kent.
Detected Chief Superintendent Jeff Rees, head of the operation, said: "This was a professional organised criminal gang."
He added: "The hostages were in a terrible state when we found them. They were sitting on the floor tied up and one had been blindfolded. They'd been beaten and were very shaken and severely traumatised."
Chinese Triad gangs have their strongholds in Hong Kong and China, but they have made inroads into all the major British cities with sizeable Chinese populations. Some Chinese criminals and young gang members in the UK have adopted the Triad tag as an attempt to obtain credibility.Reuse content