LONDON -- The immigration authorities in Britain, Belgium and France carried out coordinated raids at scores of addresses on Wednesday to round up people suspected of being members of gangs that smuggle people across or under the English Channel as stowaways in long-haul trucks.
The raids by 150 law enforcement officials in Britain alone represented "one of the biggest operations of its kind ever undertaken," said Chris Foster, a senior investigator with the United Kingdom Border Agency.
People-smuggling offers organized gangs potentially rich pickings as desperate migrants from troubled lands including Iraq, Iran and Afghanistan pay up to $10,000 each to be spirited past Britain's strict border controls and across physical barriers, particularly the English Channel.
Trucks cross the channel by ferry or through a tunnel leading from Calais in France to near Folkestone in England. Such is the desire to cross the channel that migrants, some of them children, face huge hardships.
The conservative Daily Mail reported this week, for instance, that four people ages 9 to 16 from Afghanistan and Iran tried to enter Britain in the back of a refrigerated truck carrying cheese and were treated for hypothermia when they were discovered at a port in France.
Much of Continental Europe is covered by the Schengen agreement permitting free passage across the internal frontiers of the European Union. But Britain is not a member of the agreement, and anti-immigration politicians say migrants brave restrictions and hardships to gain access to social payments, work and contact with networks of friends and relatives already in the country.
Mr. Foster said British border agents raided 35 addresses in 8 British cities on Wednesday, as French and Belgian officials carried out an additional 40 raids.
"My officers have been working closely with their counterparts in France and Belgium as well as other law enforcement agencies in the U.K. in the buildup to today's operation," Mr. Foster said in a statement.
"We believe we have successfully disrupted a significant organized network suspected of being involved in a systematic attempt to evade the U.K.'s immigration controls."
Britain's Immigration Minister, Mark Harper, said organized criminal gangs were "a major factor involved in illegal immigration to the U.K."
Immigration is a delicate political issue in Britain since the dominant Conservatives, led by Prime Minister David Cameron, face a nagging political insurgency by the United Kingdom Independence Party, which seeks to exploit suspicion of foreigners among rank-and-file voters to increase its support.
But, just this week, a scientific advocacy group warned that government efforts to curb some categories of legal immigrants will damage the economy.
In an open letter to immigration authorities, the Campaign for Science and Engineering said Britain was not training enough skilled people to fill available jobs in medical, engineering, nuclear and educational institutions.
"The skilled immigrants in these occupations help drive economic growth," the letter said. "They keep Britain's lights on by working in our nuclear industry. They save lives in our hospitals, and they educate our children."
John F. Burns reported from London, and Alan Cowell from Paris.world
This article originally appeared in The New York Times.