RIO DE JANEIRO (REUTERS) - Pope Francis arrived in Brazil on Monday on his first foreign trip as pontiff and was swarmed by well-wishers as he drove into Rio de Janeiro, where more than one million people are expected to gather to see the first Latin American to head the Roman Catholic Church.

Welcomed by a committee of local dignitaries, including President Dilma Rousseff, a smiling Pope Francis waved to onlookers before proceeding by motorcade to Rio's city center at the start of a weeklong gathering of young faithful in Brazil, home to the world's largest Catholic population.

Thousands of local Catholics, visiting pilgrims and curious Brazilians lined avenues to greet Francis, who rode in a closed car with his window open. The crush of well-wishers led to a lapse in security when crowds swarmed the car as it entered central Rio.

People surrounded the vehicle, a small silver Fiat, to take photos and touch the pontiff through his open window. Bodyguards moved in to push back the crowd, which at one point was so heavy that the car was forced to a halt.

The pope's visit to the coastal metropolis, a return to his home continent by the former Argentine cardinal, is part of the biennial World Youth Day gathering.

Despite the novelty of a new pope, the visit comes as secular interests, other faiths and distaste for the sexual and financial scandals that have roiled the Vatican in recent years cause many Catholics in Latin America and around the world to leave the Church.

The trip also comes amid growing economic and social dissatisfaction in Brazil, which is still home to more than 120 million Catholics.

The unease in June led to the biggest mass protests here in two decades as more than 1 million people in hundreds of cities rallied against everything from rising prices to corruption to poor public services.

In the five months since he succeeded Benedict, Pope Francis has pleased many with his simple style, rejection of luxuries and calls for the Church to advocate on behalf of the poor and causes of social justice. Aboard his plane on Monday, the pope told reporters the world risks losing a generation of young people to unemployment and called for a more inclusive culture.

"The world crisis is not treating young people well," Pope Francis, 76, said. "We are running the risk of having a generation that does not work. From work comes a person's dignity."

MESSAGE OF SOLIDARITY

Brazilian officials hope that his message of solidarity with the poor and working classes will minimize the possibility of major protests during his visit.

Still, they have deployed more than 20,000 soldiers, police and security officials for the visit. While some of the measures are routine security provided for any visiting head of state, they are compounded by the popular draw of the pope, especially because Pope Francis has said he plans to travel around the city in an open-top vehicle and occasionally mix with the throngs.

Some protests are already planned during the visit, mostly by feminists, gay rights groups and others who disagree with the Church's longstanding social doctrines. Brazil's recent protests, organised through social media by a disparate group of online activists, make other demonstrations likely, even if on a much smaller scale than in June.

So far, an adulatory atmosphere reigned.

Among those gathered to see the procession through central Rio, where Pope Francis switched vehicles and rode in a large white open truck, people climbed trees, bus stops and newspaper kiosks.

Thousands of people looked down from balconies and windows in the skyscrapers above.

"I felt the call of God," said Ms Mari Therese Reyes, 32, who saved money for six months in the Philippines to pay for her trip. "It's not just to see the Pope, it is an encounter with Christ."

"I love the Pope very much," said Mr Markus Hemmert, a 38-year-old German pilgrim who took three months to cycle to Brazil from Chicago.

Over the weekend, thousands of young pilgrims, many from neighbouring countries and some from as far away as China, flocked to Rio's sunny seaside during the weekend and endured long lines to visit the city's iconic Christ the Redeemer statue and Sugarloaf mountain, a giant granite monolith.

After his reception on Monday afternoon, Pope Francis is scheduled later in the week to visit a nearby shrine, call on the residents of a Rio shantytown, lead a giant service on Rio's Copacabana beach and hold Mass at a big rally in a pasture outside the city.

Ms Rousseff, a leftist whose Workers' Party has been in power since 2003, will say in her welcome speech on Monday that Brazil shares the pope's concern for the poor, according to a presidential aide. She will also point to the advances against poverty made by her administration and that of her predecessor, Mr Luiz Inacio Lula da Silva.

In private, Ms Rousseff will propose that Brazil and the Vatican join forces in international cooperation programs to fight poverty and social exclusion in Africa, the official said.

She is expected to discuss the protests with Francis if the pontiff raises the issue.

Ms Rousseff's approval ratings were among the highest of any elected leader worldwide before the protests but have plummeted since.