Human trafficking, including women forced to become prostitutes or minors forced to do child labor, is worse now than the trade in African slaves of past centuries, a top Vatican official said Tuesday.

"It's worse than the slavery of those whose slaves who were taken from Africa and brought to other countries," said Cardinal Renato Martino, former longtime Vatican envoy to the United Nations and current head of the Holy See's office concerned with migrant and itinerant peoples.

At a news conference to present Pope Benedict XVI's annual message dealing with the problems of migrants, the cardinal singled out modern-day forms of slavery — minors who are sold to do child labor or who are forced to be soldiers, as well as women forced to prostitute themselves — and challenged countries to combat these problems.

"In a world which proclaims human rights left and right, let's see what it does about the rights of so many human beings which are not respected, but trampled," the cardinal said.

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The Vatican launched an appeal for Iraqi Christian refugees during the news conference.

"I cannot forget, because of the current situation, the need for urgent measures on behalf of Iraqi Christians and other religious minorities in Iraq," said Martino's assistant on refugee and migrant issues, Monsignor Agostino Marchetto.

In the papal message, Benedict noted that more women were leaving their homelands in search of a better life. "However, women who end up as victims of trafficking of human beings and of prostitution are not few," the pope said.

In the last decade or so, many women in Eastern Europe have traveled to the West after being promised what appeared to be honest jobs, but upon arrival in the countries were forced to work as prostitute to pay off the cost of their trip.

Benedict also expressed concern over families in refugee camps.

In the camps, "there is also the risk of women and children being involved in sexual exploitation, as a survival mechanism," the pope wrote.

Senior U.N. officials said earlier this year that allegations of sexual abuse against U.N. peacekeepers remain unacceptably high and a ban on using prostitutes is meeting opposition from some troops and staff. An investigation had found that peacekeepers in Congo had sex with Congolese women and girls, usually in exchange for food or small sums of money. Cases of sexual abuse have also been reported in other peacekeeping missions from Bosnia and Kosovo to Cambodia, East Timor and West Africa.