Benedict, who will inaugurate an important regional bishops' conference during his trip, also spoke strongly against abortion during his first speech in Brazil. Speaking in Portuguese, he said he's certain that the bishops will reinforce "the promotion of respect for life from the moment of conception until natural death as an integral requirement of human nature."
Thousands of faithful waited in the cold rain for a glimpse of Benedict, then chanted "Bento, Bento" and waved flags of different South American nations as he blessed them at the monastery where he is staying.
The Vatican says Benedict will confront major challenges during his visit, such as the church's declining influence in Brazil, the rise of evangelism, and efforts to expand access to abortions in the region.
Catholic officials have been debating for some time whether politicians who approve abortion legislation as well as doctors and nurses who take part in the procedure subject themselves to automatic excommunication under church law.
The pope was asked where he stands on the issue during the flight to Brazil, in his first full- fledged news conference since becoming pontiff in 2005.
"Do you agree with the excommunications given to legislators in Mexico City on the question?" a reporter asked.
"Yes," Benedict replied. "The excommunication was not something arbitrary. It is part of the (canon law) code. It is based simply on the principle that the killing of an innocent human child is incompatible with going in Communion with the body of Christ. Thus, they (the bishops) didn't do anything new or anything surprising. Or arbitrary."
Church officials later said the pope might have inferred from the question that the Mexican bishops had issued a formal declaration of excommunication for the legislators, something Mexican Cardinal Norberto Rivera has said he has no intention of doing.
Benedict's spokesman, the Rev. Federico Lombardi, said the pope was not setting a new policy and did not intend to formally excommunicate anyone - a rare process under church law that is separate from the doctrine of self-excommunication.
"Since excommunication hasn't been declared by the Mexican bishops, the pope has no intention himself of declaring it," Lombardi said. But Lombardi added that politicians who vote in favor of abortion should not receive the sacrament of Holy Communion. "Legislative action in favor of abortion is incompatible with participation in the Eucharist. ... Politicians exclude themselves from Communion," he said. Pressed again to say whether the lawmakers had been excommunicated, Lombardi reiterated: "No, they exclude themselves from Communion." Excommunication is the severest penalty the Roman Catholic Church can impose on its members. When someone is excommunicated "his status before the church is that of a stranger," the New Advent Catholic Encyclopedia says. In practical terms, that means the excommunicated person is forbidden from receiving the sacraments and participating in public worship. Church teaching says anyone who has an abortion is automatically excommunicated. "Being a conspiring or necessary accomplice" to an abortion also means excommunication under church law. The Mexican politicians who supported the measure shrugged off Benedict's comments Wednesday. "I'm Catholic and I'm going to continue being Catholic even if the church excommunicates me," said leftist Mexico City lawmaker Leticia Quezada. "My conscience is clean." On the plane from Rome, Benedict said the exodus of Catholics for evangelical Protestant churches in Latin America was "our biggest worry." But he said that the spread of Protestantism shows a "thirst for God" in the region and that he intends to lay down a strategy to answer that call when he meets with bishops from throughout Latin America in a once-a-decade meeting in the shrine city of Aparecida near Sao Paulo. "We have to become more dynamic," he said. Evangelical Protestant churches have attracted millions of Latin American Catholics in recent years. The Vatican also has promised that Benedict will deliver a tough message on poverty and crime during his five-day visit to Brazil - the world's most populous Roman Catholic country. Benedict's predecessor, John Paul II, visited Mexico and addressed Latin American bishops just three months after assuming the papacy. Benedict has waited two years for his first trip to a region with nearly half the world's 1.1 billion Catholics. But he denied being "Eurocentric" or less concerned about poverty in the developing world than his predecessors. "I love Latin America. I have traveled there a lot," he told reporters, adding that he is happy the time had come for the trip after focusing on more urgent problems in the Middle East and Africa. Benedict, who visited Brazil as then-Cardinal Joseph Ratzinger in 1990, will celebrate several open-air Masses, including a canonization ceremony for Brazil's first native-born saint, and visit a church-run drug and alcohol rehabilitation center. Marcelo Zapata, 19, flew from Chile in hopes of glimpsing the pontiff. "The pope is the representative of Christ on Earth and I'm emotional about meeting him," he said. "I never met any other pope and this may be the only time he'll come to Latin America because he's already 80 years old." Ivany Yazbek, 49, managed to touch the hand of John Paul II when he visited Brazil in 1980. "I don't know if this pope will be as charismatic as the other pope, but we'll find out," Yazbek said. Shivering in the cold, Edmundo Barbosa, a 32-year-old salesman, said, "I just want to see what he looks like, and if I could talk to him I'd ask for peace." AP-CS-05-09-07 1840EDT