The network, which operates in west London suburb of Southall which has a large population of Punjab-origin, allegedly exploits hundreds of illegal immigrants from India through cheap housing, faked documents and poorly paid, often dangerous jobs.

The BBC report showed the facilitators speaking in Punjabi, collecting money for illegal services provided and handing over the key identity documents such as passports and the National Insurance card.

During the investigation, widespread unlawful job practises, squalid housing, and a thriving trade in fake documents were uncovered. More than 40 houses packed with illegal immigrants were identified in one square mile of Southall, the report said.

"The young, mostly male Punjabis are not here lawfully and, although most know the risks, they have few legal rights.

They are surrounded by forgers, criminals and ruthless employers," it said.

A team of BBC's undercover reporters met and filmed a man who called himself 'Vicki', who was open about the fake documents he could obtain, and boasted about servicing customers in Sheffield, Bradford and Coventry.

Vicki told reporters that he could get people into the country on lorries, known as donkeys, organised by what he called his "man in Paris", and how he could provide a fake "original" passport that had been "checked" to beat security at a UK airport.

The Indian illegal immigrants, known within the network as 'faujis', find work in Southall but often at rates below the national minimum wage.

The report mentioned the case of a 'fauji' being employed for 12-hour days, six days a week at 150 pounds, or about two pounds an hour.

Last week, the London mayor, Boris Johnson, announced a raise in the living wage for London to seven pounds and 45 pence per hour, which is 35 per cent higher than the national minimum wage.

"This hidden community is an open secret - landlords take on tenants, employers want cheap and uncomplaining labour, while the criminals trade in people's lives.

"Once the undercover reporters infiltrated this closed community, it was clear how easy it is to remain invisible.

One clear fact remains: the scale.

"In just one square mile, hundreds of illegal immigrants, scores of multiple-occupancy houses, and people dealing in fake identities, employment and fraud. A criminal network that is out of sight," The BBC reported.