A Texas woman has been indicted on charges she allegedly sold her 15-year-old daughter for $US3000 ($3600) to a man accused of child sex crimes.

Tina Valdez, 37, reported her daughter missing to authorities in August, claiming the girl had run away and was searching for her father, Archer County Sheriff Ed Daniels said.

But last month, after US authorities had located and spoken to the teenager - who was in Mexico - Valdez told investigators she sold the girl, Daniels said. The alleged admission came while police were interviewing Valdez about filing a false report about her daughter being a runaway, he said.