More poor children may be driven into the sex trade as a result of the world financial crisis and the spreading use of the Internet by predators to find victims, participants at a U.N.-backed conference said Wednesday.

Those factors pose new challenges for governments, which must do more to combat abuse and growing child prostitution, said Ann Veneman, executive director of UNICEF.

"Poverty contributes to it," Veneman said in a telephone interview from Rio de Janeiro, where U.N. agency is a co-sponsor of this week's Third World Congress against Sexual Exploitation of Children and Adolescents.

"You are more likely to have demands on children to drop out of school, and if they are young girls, they are very likely to end up in prostitution or being sexually exploited."

More than 3,000 conference participants, including government representatives from 137 nations, will try to determine how best to fight child sex abuse. One topic: how law enforcement agencies can work with credit card companies to target predators who use cards to pay for sex tourism and child pornography.

Brazil is a sex tourism destination with long-standing child prostitution problems involving both foreign and Brazilian clients. President Luiz Inacio Lula da Silva signed a decree just before the congress that boosts the minimum child pornography prison sentence from two to four years.

Silva said sex education should be mandatory for children starting at age 10. He faulted the news media for showing too much sex on TV and said that rich and powerful exploiters who force children into prostitution must be punished.

Child sex abuse shouldn't be blamed on poverty alone because the global sex trade depends on educated middle-class men "who want to satiate their beastly appetites," Silva said in comments released Wednesday by the presidency.

The International Labor Organization estimated at least 1.8 million girls and boys under age 18 were involved in the global sex trade in 2000, and nobody knows how much it has grown since then.

The conference also focuses on children who are forced to have sex but are not involved in prostitution or pornography — issues such as the rape of girls during conflicts in Africa, the child-bride trade in Yemen and abuses by parents and priests around the world.

A recent U.N. survey estimated that 150 million girls and 73 million boys under age 18 were forced to have sexual intercourse or experienced other forms of sexual violence in 2002.

"There is a growing problem around the world of more girls on the streets," Veneman said. "You have to look at the demand side of the equation: Men are a big part of the problem and they have to be part of the solution."

In the largely lawless Amazon region state of Para, some families prostitute their daughters to truckers because it's often the only way they can get enough money to eat, said federal police superintendent Ismar Ferreira.

He blamed a lack of social programs for preventing the practice, and said some cases end up as sexual slavery.

"I found a 72-year-old man living with an 11-year-old girl he got in a trade for a sack of flour," Ferreira told the Agencia Brasil news agency.

Last year, a 15-year-old girl arrested on petty theft charges was left for weeks in a jail cell in Para state with 21 men, who raped her, tortured her and only allowed her food in exchange for sex.

The case exposed the fact that Para, a state twice the geographical size of France, still only has six separate cells for women at its 132 jails.