The four-day sweep in the US, which ended on Sunday, was the 11th annual effort by the FBI and other authorities to battle child sex trafficking.

:: US authorities have rescued 84 children, one just 3 months old, and arrested 120 people in a nationwide sweep of child sex trafficking that exposed the growing use of technology by traffickers, officials said on Thursday.

Many of those arrested were advertising and selling children online for sex, said the Federal Bureau of Investigation (FBI) and National Center for Missing and Exploited Children (NCMEC) in a statement.

The four-day sweep, which ended on Sunday, was the 11th annual effort by the FBI and other authorities to battle child sex trafficking.

Called Operation Cross Country XI, it was conducted at hotels, casinos and truck stops, as well as street corners and Internet websites, they said.

“The sad reality is some things stay the same, that there’s still a need to do this,” said Staca Shehan, executive director of the NCMEC’s case analysis division.

“What has changed over time is the places and the ways that child sex trafficking is occurring,” she told the Thomson Reuters Foundation.

“Historically, kids would be recruited in face-to-face environments, at malls and at bus stops or in schools or in and around foster homes,” she said.

“All that stuff happens, but now what we see more often than not is kids are recruited online, and they’re controlled online and sold online.”

Babies, toddlers, teens

The average age of the children caught up in the operation was 15, authorities said.

The 3-month-old girl and a 5-year-old girl were offered to an undercover officer in Denver for sex for $600, the FBI said.

The person trying to sell them was a friend of the children’s family.

Related operations were conducted in Canada, Britain, Thailand, Cambodia and the Philippines, the FBI said.

The sweep also involved the arrests of a number of adult sex workers, including 20 prostitutes in the state of Oregon.

Earlier incarnations of Operation Cross Country have come under criticism by advocates for sex workers who say they are victims of exploitation and should not be charged with crimes.