The raids were connected to a 2-year-old police and FBI investigation into the sex trade tied to Asian organized crime, police said.

"This is not just one or two gangbangers who have one or two girls working for them," said officer Bill Cassell, spokesman for the Las Vegas police.

"This is true organized crime. They are preying on these women who are possibly forced into lives of prostitution against their will."

The seven suspects, mostly men, were arrested on various prostitution-related charges. Authorities were interviewing the 25 prostitutes taken into custody to see whether they were victims or suspects in human trafficking, Cassell said.

"This goes back to countries other than the United States," he said.

Police didn't release the names or nationalities of those arrested.

David Staretz, a supervisory special agent for the FBI in Las Vegas, said Sunday evening that federal authorities were continuing to investigate the case.

"We're looking to see if there is any nexus between organized crime and human trafficking within the city and state," he said.

Federal officials estimate that more than 17,500 people are brought to the United States each year for illegal purposes. Federal officials previously said that the Las Vegas Valley is one of 17 communities in America at a high risk for trafficking of humans.

In December, a new office, the Anti-Trafficking League Against Slavery, opened within the Metropolitan Police Department to combat human trafficking in the Las Vegas Valley.