More than five million barefoot devotees paraded a centuries-old icon of Jesus Christ through Manila Friday in a loud, heaving paroxysm of religious fervour ahead of Pope Francis' visit to Asia's bastion of Christianity.

In fervent displays of devotion, huge crowds of men, women and children chanted "Viva!" (Long live!) and twirled white handkerchiefs at the Black Nazarene, with some hurling themselves at the supposedly miraculous statue for good luck.

"The Lord is my healer," Lina Javal, 58, declared after waiting in line for hours to kiss the life-sized ebony statue, showing an AFP reporter the healed incision from throat surgery she underwent last month.

"It's an extraordinary feeling, it's like the Holy Spirit is entering my body," said the clerk from nearby Laguna province.

The mammoth procession, estimated by the Philippine Red Cross at 5.5 million people, crawled at a near-snail's pace along Manila's old quarter as devotees risked life and limb for the privilege of pulling the fat rope that moved the float forward.

City officials and the Philippine Red Cross said a man died from heart attack and more than 600 others were treated for various injuries as the crowd wriggled past trash-strewn streets in light rain and overcast skies.

The procession is expected to last well into the night.

"I pray that the Nazarene continues watching over my grandson, that he is kept healthy," Manila laundrywoman Imelda Santiago, 62, told AFP.

She carried the two-year-old boy, who is blind in his right eye, to the parade, shielding him from the rain with a blanket.

Many Filipinos believe the statue holds miraculous healing powers and make lifetime vows to join the annual parade, often wearing T-shirts emblazoned with an image of Christ crowned in thorns.

"The brand of religious devotion that we see in Filipino Catholicism is based on a very strong desire of the majority of our people for a more immediate and direct access to divine help or power," Manuel Victor Sapitula, a sociology professor at the University of the Philippines, told AFP.

"That is why it is sought through physical touch, sound, bodily experience, or any combination of these," he added.


'Extreme piety'

The Philippines is also host to some other forms of extreme piety, including ritual crucifixion of more than a dozen devotees at a farming village north of Manila each Good Friday, when male penitents wearing black masks and crowns of thorns also whip their backs bloody with strips of bamboo.

Isko Moreno, the vice mayor of Manila city, told ABS-CBN television that about a million people took part at the start of the procession, and many more waited to join it along a circuitous route.

Eight in 10 of the Philippines's 100 million people are Catholics, and the Black Nazarene festival is a display of the vibrance of the religion ahead of the papal visit which begins on January 15.

During his January 15-19 trip, Pope Francis will comfort victims of deadly Super Typhoon Haiyan in central Leyte island, and celebrate mass for millions in the capital's largest outdoor park.

First brought to Manila by Augustinian priests from Mexico in 1607, decades after the archipelago was colonised by Spain, the Nazarene statue is believed to have acquired its colour after it was partially burnt when the galleon carrying it caught fire.

Construction worker Angelo Pamarca, 30, walked an hour to join the procession with his six-year-old daughter perched on his shoulders.

"I ask the Black Nazarene to forgive my many sins and give me strength to resist temptation," Pamarca told AFP with a mischievous grin, declining to elaborate.

Aileen Amandy, 48, joined the parade with her teenage daughter to seek divine intervention in helping her children complete their studies.

"He always grants my prayers," Amandy said, crediting the Black Nazarene with healing a son suffering from high fever and convulsions, and keeping another son, a policeman, safe from harm.