By Julia Houston BBC News, Liverpool

Illegal immigrants are forced to work in the sex and fast food trades

Instead, they are now forcing illegal immigrants to work in one of the hundreds of Chinese restaurants in the North West - or channelling them into the sleazy world of illegal brothels and massage parlours.

Police say the gangs smuggle people into the UK, promising them a better life in a country where well-paid jobs are easy to get.

But the Chinese business leaders say once here they are forced into illicit work, as immigration rules make it impossible to work legally.

Restaurants badly need people but they can't get people to work Simon Wong

Det Supt Ian Foster, of the Greater Manchester force, said it is difficult to smash the gangs' operations.

"Some of them come under false pretences thinking they're coming to a better life, and when they get here they can be taken into the sex industry against their will," he said.

"What we do know is that this country is very attractive to people from countries that might have poor economic backgrounds," he said.

Simon Wong, who works in Hondo's supermarket in the heart of Liverpool's Chinatown, said it is when people come to the UK and are not granted the papers to work legally that the problems start.

"We are hard working people, but today we have too many bad things happening," he said.

"All this can be very damaging to our community, because people cannot find work - how are you expecting they find work through the legal channel?

"As employers, we would like to help them but we cannot employ those people. Restaurants badly need people but they can't get people to work.

Brian Wong wants to protect the community's identity

"It is bad for the business, bad for the country, it is no good for nobody, except it makes the illegal workers flourish."

His brother, Brian Wong, is head of the Chinese Business Community in Liverpool.

He said there seems to be fewer immigrants coming to the city these days, but those who do come to work illegally tarnish the image of a harmonious community.

"Our concern is for the image of the Chinese community in Liverpool," he said.

"We all live in harmony with other communities, and the image we have after the cockling disaster means we have a negative identity - it has had an impact on our quiet life.

We are making inroads into it, and we have had some successes Det Supt Ian Foster

"We, as a community, should send a message to people to make sure the illegal immigrants and their activities should not be accepted in modern society."

But Mr Foster said these people are attracted to the larger cities, such as Liverpool and Manchester, because it is easier for them to blend in to the community unseen.

"It is very much is a clandestine community," he said.

"A lot of these things are passed by word of mouth within family or friends, and it is very hard to break into that sort of secret world to find out just how it's being done.