The biggest raid in London this year on illegal workers has led to more than 30 arrests in Chinatown.
About 60 raids on illegal workers are taking place in London weekly
The area was brought to a standstill as five restaurants were raided during the busy lunchtime period on Thursday.
Shocked passers-by stopped and stared as more than 100 arrest-trained immigration staff and police stormed the Soho premises.
The exact number of people detained will be confirmed by the Border and Immigration Agency (BIA) later.
Chinese, Malaysian and Singaporean nationals were arrested and documents relating to illegal employment seized.
Two Malaysian nationals were already set to fly back to their home country following the operation.
Malcolm Leow, 23, an accountant who came to London from China two months ago, witnessed the raids.
Royal Dragon, Gerrard Street
Luxuriance Peking, Gerrard Street
Golden Dragon, Gerrard Street
Hong Kong, Lisle Street
Special Zone, Wardour Street
He said: "I think if they're coming here illegally they're probably doing it because they need to make money to send back home.
"Britain is a good choice because the pound is strong."
Tony Smith, the BIA's regional director for the South East said about 60 raids on illegal workers were taking place in London each week.
"The BIA is very anxious to crack down on those who facilitate the entry of illegal workers for financial gain and then exploit them with poor wages and working conditions," he said.
"And we're targeting the employers, not just the workers.
Earlier this year the Home Office announced an action plan to target rogue employers.
New unlimited fines for those who employ illegal workers will be placed before Parliament for approval later this month.
The raids were part of a wider strategy by the BIA to clamp down on illegal workers - some of whom pay thousands of pounds to be trafficked to Britain by gangs who then exploit them.
Chinese Triad and Snakehead gangs are known to be major players in this underworld labour trade.
The number of Chinese nationals entering the UK each year illegally has been estimated at 50,000 - but a Home Office spokesman said there was no official figure.