Dozens of raids have been carried out across the country as part of one of the biggest-ever crackdowns on people-smuggling.
Officers from the UK Border Agency (UKBA) raided 35 addresses in England, targeting gangs who bring illegal immigrants into the country in the back of lorries through Channel ports.
By Wednesday afternoon, 20 people had been arrested after raids were carried out in London, Hampshire, Peterborough, Birmingham, Coventry, Smethwick, Leamington Spa, and Stoke-on-Trent. Warrants were also executed in Manchester, Sheffield and Lancashire.
Another six people were arrested for unrelated offences including alleged immigration breaches. More than 150 officers from the UKBA took part in the operation. It is understood many of the immigrants who pay the gangs are from Iraq, Iran and Afghanistan.
Chris Foster from UKBA said: "We believe we have successfully disrupted a significant organised network suspected of being involved in a systematic attempt to evade the UK's immigration controls."
Immigration Minister Mark Harper said: "The organised criminal gangs involved in people-smuggling prey on the desperation of others in order to line their own pockets. They are also a major factor involved in illegal immigration to the UK."
The 20 men arrested in connection with the investigation included nine aged 19 to 33 who were held in London in Stockwell, Wood Green, Peckham, Southall, Manor Park, Peckham, East Ham, South Croydon and Harrow.
Another four aged 18 to 33 were arrested in the Midlands in Smethwick, Birmingham and Coventry; and three aged 20, 21 and 25 were held in Peterborough. The remaining arrests were of a 38-year-old in Manchester, a 27-year-old in Leigh, Lancashire, a 36-year-old in Sheffield and a 31-year-old in Fareham, Hampshire.
The other six not relating to the investigation were five men who were held on suspicion of immigration offences in Manor Park, east London, Southall, west London, and Palmers Green, north London. The sixth was a man who was arrested for ID card offences in Southsea, Hampshire.