A major U.S. law enforcement operation, which saved over 100 minors from prostitution rings and arrested over 150, drew praise from a congressman known for toughening laws against sex trafficking.

The raids were "simultaneously sad and heartening," said Rep. Chris Smith (R-N.J.), co-chair of the Congressional Human Trafficking Congress.

"Those children are freed from a terrible life of misery, but these crimes would not occur without the demand of buyers of commercial sex," he told CNA July 30.

"It is my hope that law enforcement also caught buyers among the 150 arrests, and that it will seek justice to those who obtain children for commercial sex."

Launching on July 26, the FBI and 230 separate law enforcement agencies took part in Operation Cross Country in 76 cities across the U.S. The children rescued were almost all girls and ranged from 13 to 17 years old.

The largest numbers of children were saved in the FBI divisions based in San Francisco, Detroit, Milwaukee, Denver and New Orleans. Those arrested include 150 alleged pimps.

Ron Hosko, assistant director of the FBI's Criminal Investigative Division, said that child prostitution remains "a persistent threat to children across America."

"This operation serves as a reminder that these abhorrent crimes can happen anywhere, and the FBI remains committed to stopping this cycle of victimization and holding the criminals who profit from this exploitation accountable," he said July 29.

The operations often began as local law enforcement actions against truck stops, casinos, and websites that advertise dating or escort services, the FBI said. Initial arrests for violations of local and state laws help uncover organized prostitution efforts across different states.

About 2,700 children have been rescued in similar raids since 2003.

Teen runaways are particularly vulnerable to being lured into prostitution. Many sex trafficking victims are runaways from foster care or group homes, the National Center for Missing and Exploited Children said.

Rep. Smith, author of the Trafficking Victims Protection Act of 2000, said his legislation "comes down hardest on those who traffic children." Those who violate its provisions could face life in prison.