Immigration officers and police have detained five people in one of the largest crackdowns against bogus marriages.
About 30 officers were involved in the Scottish operation
The officers carried out early morning raids on addresses in Scotland and the south east of England as part of Operation Warren.
Two males, aged 27 and 22, and a 26-year-old female were detained in Scotland.
Officers said males aged 33 and 35 were detained in England.
They said West Africans have been arranging bogus marriages to vulnerable British citizens, such as drug addicts and prostitutes, to gain entry to the UK under false pretences.
Operation Warren was spearheaded by raids on homes in Cambuslang and Paisley at about 0600 BST on Friday.
More than 30 officers from the Border and Immigration Agency and Strathclyde Police took part in the Scottish raids.
Similar raids were carried out in Thornton Heath, south of London, and also at properties in Reading.
Phil Taylor, the Border and Immigration Agency's regional director for Scotland and Northern Ireland, said the operation had been a success.
He told the BBC Scotland news website: "We believe that this is one of the biggest fraudulent marriages scams against immigration controls conducted for some years.
"The investigation we have conducted is of a major scale. The registrars would identify cases which they believe to be shams and we would deal with those cases.
"We don't know why it's a problem in this area but it is not unusual for immigration crime to be specific to some nationalities.
"The scam operates by people who are lawfully in the country but seeking to gain settlement here identifying individuals who are resident in the UK who are prepared to go through marriage for payment but with no intention of living together."
Chief Inspector Jim Boyle, of Strathclyde Police, said the operation started in September last year.
He said: "The people involved in organising the scam have targeted people involved in vice and drugs, people who are struggling to get money.
"They are used as spouses for individuals who want to remain in the UK illegally. This has been quite a complex operation.
"The organisers have been quite clever in the way they have gone about it."