"Millions of people around the world living with and affected by HIV are being supported by Catholic health care organizations," Sidibe said. "The full engagement of the Catholic Church in efforts to achieve zero new HIV infections among children is of paramount importance."

The U.N. agency noted that the Vatican has estimated Catholic agencies provide about 25 percent of all HIV treatment and care throughout the world. And the World Health Organization has estimated that perhaps as much as 70 percent of all health care in Africa is provided by faith-based organizations.

In addition to his brief meeting with Pope Benedict at the end of the pope's weekly general audience, Sidibe also met with Cardinal Peter Turkson, president of the Pontifical Council for Justice and Peace, and with Michel Roy, secretary-general of Caritas Internationalis.

After the meetings, he told Vatican Radio the influence and reach of churches and other faith-based groups have a huge potential "to fight stigma and discrimination and also to inform people that being sexually responsible is important when you want to prevent new infections" with the virus that causes AIDS.

He said Catholic parishes also can encourage women to get tested for HIV, offer support to those who are positive, let them know treatment is available and encourage them to get the antiretroviral drugs when pregnant to prevent passing the virus on to their children.

The last U.N. High-Level Meeting on HIV/AIDS pledged to focus on preventing mother-to-child transmission of HIV, particularly by stepping up the offer of antiretroviral treatments to pregnant women in the 22 countries that together account for 90 percent of all new infections of children worldwide.

Sidibe told Vatican Radio, "You can save the mother and at the same time avoid the baby being born HIV-positive and give that child a chance to grow without being an orphan."