Manila, Jan 19 (Agencies) : A record six million people poured into Manila's rain-soaked streets and its biggest park as Pope Francis ended his Asian pilgrimage with the biggest-ever papal mass.

The crowd estimate included people who attended the Pope's final Mass in Rizal Park and surrounding areas, and lined his motorcade route, said officials in the Philippine capital.

It came after the pope was earlier challenged by a 12-year-old orphan girl to explain how God could allow innocent children who have done nothing wrong to be dragged into lives of drug addiction and prostitution.

Francis marked an important feast day honouring the infant Jesus by dedicating the final homily of his week-long Asian trip, which began in Sri Lanka, to children. It was a reflection of the importance the Vatican places on Asia as the future of the church since it is one of the few places where Catholic numbers are growing. The Philippines is the largest Catholic nation in the region.

'We need to see each child as a gift to be welcomed, cherished and protected,' Francis said in his homily. 'And we need to care for our young people, not allowing them to be robbed of hope and condemned to a life on the streets.'

He urged the crowd to protect their children from sin, alcohol and gambling, saying the devil 'distracts us with the promise of ephemeral pleasures, superficial pastimes'.

The Pope's last full day in the Philippines began with a youth gathering at a Catholic university in Manila, where attendees were moved by a question posed by a 12-year-old orphan girl.

Glyzelle Iris Palomar asked him: 'Many children are abandoned by their parents. Many of them became victims and bad things have happened to them, like drug addiction and prostitution. Why does God allow this to happen, even if the children are not at fault? Why is it that only a few people help us?'

The girl, who was rescued and found shelter in a Church-run community, broke down in tears and could not finish her prepared welcome. The Pope hugged her and later put aside most of his own prepared speech to respond.

'She is the only one who has put forward a question for which there is no answer and she was not even able to express it in words but rather in tears,' he said, visibly moved.

'Why do children suffer?' the Argentine Pope said, speaking in his native Spanish. An aide translated his words into English for the crowd of about 30,000 young people on the grounds of the Church-run university.

'I invite each one of you to ask yourselves, "Have I learned how to weep, how to cry when I see a hungry child, a child on the street who uses drugs, a homeless child, an abandoned child, an abused child, a child that society uses as a slave?"'