Spanish police say they have busted a gang of 25 Nigerians who were engaged in human trafficking for sexual exploitation, Internet fraud and money laundering.

Five women victims of sex slavery also were released during the crackdown on the underground operation in Spain, the police said in a statement Sunday.

The gang was using Spain as a springboard to send Nigerian women to be exploited in other countries, and it laundered profits by buying luxury products that were shipped to Lagos, Nigeria, in vans with darkened windows and welded doors, police said.

The crackdown seized 94 vans near Madrid and 26 loaded ones at Valencia port containing goods with an estimated value of $6.7 million, the statement said. Police had to use heavy machinery to open the vans, which contained items such as expensive television sets and cases of premium liquor.

The gang was originally formed around 1990 at Nigerian universities and was responsible for sending a large number of "Nigerian letters" that tried to fraudulently extract money from recipients, the statement said.

The gang "captured" women in Nigeria, flew them with false identity papers to airports in Mexico and Brazil, then sent them to Paris, from where they were driven to Spain, police said.

Eight of the 25 suspects were illegal immigrants, and the arrests occurred in Madrid, Toledo, Cantabria and Palma de Mallorca. The statement didn't say when that happened.