Child prostitutes face many dangers on the streets
More than 600 adults have been arrested in raids across the US targeting people who force children into prostitution.
Operations took place in 29 cities in a co-ordinated action involving federal, state and local law officers, according to the FBI.
Officials said 12 large-scale prostitution rings were dismantled in the raids and 47 children rescued.
Since 2003, 575 child prostitutes have been saved from exploitation by American criminal gangs, they added.
Officials said many of the prostitution rings broken up were operated through call centres, truck stops, casinos and websites.
The FBI generally gets involved in child prostitution cases that cross state lines.
At a news conference announcing the results of Operation Cross Country II, FBI Deputy Director John Pistole said the arrests were made possible by intelligence gathered during similar raids in June.
"Sex trafficking of children remains one of our most violent and unconscionable crimes in this country," he said.
The 47 rescued children range in age from 13 to 17, and all but one are female.
Of these, Mr Pistole said, 10 had been reported to the National Center for Missing and Exploited Children.
A total of 642 people were arrested. They included 73 pimps and 518 adult prostitutes, according to the FBI.
Correspondents say child prostitution has become an urgent issue in recent years, as demonstrated by the growth of online networks where pimps advertise youngsters to clients.
A recent University of Pennsylvania study estimated that nearly 300,000 children in the US are at risk of being sexually exploited for commercial purposes.
"Make no mistake, the minors who were interdicted as a part of this operation are victims of the most extreme form of sex trafficking," said acting Assistant Attorney General Matthew Friedrich.
"It sadly remains the case even now in 2008 that there remain instances of children in the United States manipulated into prostitution by pimps willing to make a fast buck based on the most vulnerable among us," he said.