About 16,000 minors have suffered sexual abuse in Mexico, mostly in urban areas, the National System for Holistic Family Development (DIF) said.
Speaking at the opening of a conference called the "Sex Trade in Urban Areas: Origins and Perspectives", DIF President Ana Rosa Paya said on Wednesday that 5,000 cases, or nearly one in three of the reported child abuse cases, took place in Mexico City.
There is a growing risk of illegal trade in child sex abuse, she added.
"These figures are something we cannot ignore and that demands our protection of our children."
Mexican police have detected between 72,000 and 100,000 pornographic websites, the DIF president said.
"We must find ways to make sure that child abusers and prostitution rings are not tolerated," Paya said.
According to the official, 10 per cent of child prostitution took place in working-class areas like La Merced, Garibaldi and Centro Historico, where adult prostitution is an established tradition.
The DIF president said in La Merced -- a sprawling market surrounded by slums -- there are more than 2,000 prostitutes, of whom half are underage.
Paya said 34 hotels in the area have made money from sex trade and that they typically make 100,000 Mexican pesos ($9,090) a month.