Rio de Janeiro  - The use of the internet to spread child pornography and to find victims for the sex trade pose new challenges for governments, the head of UNICEF said at a global conference on child sexual exploitation.

"Parents and children must prepare themselves better for the risks of the internet," Ann Veneman, UNICEF executive director, said Wednesday in Rio de Janeiro.

The main goal of the more than 3,000 conference participants, including government representatives from 125 nations, is to increase cooperation between companies and governments to tackle the growing problem of internet child pornography.

To be discussed is how law enforcement agencies could work with credit card companies to target predators who use cards to pay for sex tourism and child pornography.

Brazilian President Luiz Inacio Lula da Silva opened the Third World Congress against Sexual Exploitation of Children and Adolescents on Tuesday by signing a measure that stiffens the minimum child pornography prison sentence from two to four years. Brazil is known as a sex-tourism destination.

In his opening speech, Silva said sex education should be mandatory for children starting at age 10, saying it "is as important an obligation as it is to give food every day to the children so they can survive."

He added that child sex abuse shouldn't be blamed on poverty alone as the global sex trade depends on educated middle-class men "who want to satiate their beastly appetites."

According to the International Labor Organization, an estimated 1.8 million girls and boys were involved in the global sex trade in 2000. No one knows how much it has grown since then.

Queen Silvia of Sweden, who wants to make it illegal to systematically look at child pornography in her country, said at the conference that the exploitation of children has many facets and they all are "equally shocking." She founded the World Childhood Foundation in 1999 to protect children from sexual abuse.

The conference also is focusing 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.

The international network ECPAT, or End Child Prostitution, Child Pornography and the Trafficking of Children, is demanding that all businesses and institutions adopt child protection guidelines that would prevent the downloading of child pornography.

Faster acting and more widespread cooperation is needed, ECPAT representative Amihan Abueva said. "Often, these are very easy measures to put on paper, but we must act to enforce them," Abueva said.

The last conferences against the sexual exploitation of children were held in Japan in 2001 and in Stockholm in 1996. (dpa)