Image caption "The FBI remains committed to stopping this cycle of victimisation," Ron Hosko said

The FBI says it has rescued 105 children and arrested 150 pimps in 76 US cities over the weekend, in an operation against child prostitution.

The largest numbers of children rescued were in San Francisco, Detroit, Milwaukee, Denver and New Orleans.

FBI assistant director Ronald Hosko said the Operation Cross Country VII raids had been the agency's largest action against child exploitation.

The FBI said 2,700 children have been rescued in such US raids since 2003.

The victims in the most recent raids were almost all girls and range in age from 13 to 17.

They had been prostituted in a variety of locations, including truck stops, casinos, motels as well as on social media and online advertisements.

Mr Hosko said the accused had preyed on vulnerable teenagers, exploiting them over a period of time.

"Girls are enticed with compliments or offers, [asked] do they want to make some money," he said.

"Then they are trapped into this cycle that involves drugs, that involves physical abuse. It may involve torture."

Since 2003, some 1,350 people have been convicted in such cases, including life prison sentences for 10 pimps, the FBI said.

Assets of more than $3.1m (£2m) have been seized.

The US justice department has estimated as many as 450,000 children run away from home each year.

It says a third of teens living on the street will be lured toward prostitution within 48 hours of leaving home.

Some lawmakers have said further legal protections are needed.

Oregon Senator Ron Wyden has introduced a bill to require local police, as well as foster care and child welfare programmes to identify children lured into sex trafficking as victims of abuse and neglect, making them eligible for protection and services.

"In much of the country today if a girl is found in the custody of a so-called pimp she is not considered to be a victim of abuse, and that's just wrong and defies common sense," Sen Wyden said during a hearing last month.