Pope Francis issued his strongest defence yet of church teaching opposing artificial contraception on Friday, using a rally in Asia's largest Catholic nation to urge families to be "sanctuaries of respect for life."

Francis also denounced the corruption that has plagued the Philippines for decades and urged officials to instead work to end its "scandalous" poverty and social inequalities during his first full day in Manila, where he received a rock star's welcome at every turn.

Security was tighter than it has ever been for this pope, who relishes plunging into crowds. Cellphone service around the city was intentionally jammed for a second day on orders of the National Telecommunications Commission and roadblocks along Francis' motorcade route snarled traffic for kilometres.

Police vans followed his motorcade while officers formed human chains in front of barricades to hold back the tens of thousands of wildly cheering Filipinos who packed boulevards for hours just for a glimpse of his four-door Volkswagen passing by.

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Pope Francis addresses thousands of the faithful at the Mall of Asia arena in Manila on Friday. He is on a five-day apostolic visit in the predominantly Catholic Philippines. (Wally Santana/Associated Press)

Police said another 86,000 gathered outside one of Manila's biggest sports arenas, capacity 20,000, where Francis held his first encounter with the Filipino masses: a meeting with families. There, he firmly upheld church teaching opposing artificial contraception and endeared himself to the crowd with off-the-cuff jokes and even a well-intentioned attempt at sign language.

Francis has largely shied away from emphasizing church teaching on hot-button issues, saying the previous two popes made the teaching well-known and that he wants to focus on making the church a place of welcome, not rules. But his comments were clearly a nod to the local church, which recently lost a significant fight when President Benigno Aquino III pushed through a reproductive health law that allows the government to provide artificial birth control to the poor.

"Be sanctuaries of respect for life, proclaiming the sacredness of every human life from conception to natural death," Francis exhorted the crowd. "What a gift this would be to society if every Christian family lived fully its noble vocation."

He then deviated from his prepared remarks to praise Pope Paul VI for having "courageously" resisted calls for an opening in church teaching on sexuality in the 1960s. Paul penned the 1968 encyclical "Humanae Vitae" which enshrined the church's opposition to artificial birth control.

Francis noted that Paul was aware that some families would find it difficult to uphold the teaching and "he asked confessors to be particularly compassionate and understandable for particular cases."

But he nevertheless said Paul was prescient in resisting the trends of the times.

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Pope Francis greets people as he arrives for a meeting with families at the Mall of Asia arena in Manila, Philippines on Friday. (Osservatore Romano/Associated Press)

"He looked beyond. He looked to the peoples of the Earth and saw the destruction of the family because of the lack of children," Francis said. "Paul VI was courageous. He was a good pastor. He warned his sheep about the wolves that were approaching, and from the heavens he blesses us today."

Francis also urged families to be on guard against what he called "ideological colonization," an apparent reference to gay marriage, which isn't legal in the Philippines. The church opposes gay marriage, holding that marriage is only between man and wife.

On Saturday he travels to the central Philippines to comfort survivors of the 2013 Typhoon Haiyan, which left more than 7,300 dead and missing and destroyed entire villages.