Pope Francis on Friday challenged politicians in the Philippines to end "scandalous social inequalities", as he called on them to show integrity and reject corruption.
Addressing the country's most senior politicians, clergymen and diplomats at the presidential palace, Pope Francis did not mince his words as he demanded that leaders "be outstanding for honesty, integrity and commitment to the common good".
"Reforming the social structures which perpetuate poverty and the exclusion of the poor first requires a conversion of mind and heart," the 78-year-old pontiff said.
"I hope that this prophetic summons will challenge everyone, at all levels of society, to reject every form of corruption which diverts resources from the poor, and to make concerted efforts to ensure the inclusion of every man and woman and child in the life of the community."
The pontiff said politicians should hear the voice of the poor.
"The great biblical tradition enjoins on all peoples the duty to hear the voice of the poor. It bids us break the bonds of injustice and oppression which give rise to glaring and indeed scandalous, social inequalities," he said.
It was the Pope's first major speech in his five-day visit and is especially poignant for the Philippines, a bastion of Catholic piety that has ironically been also plagued by decades of graft that has made it one of the region's poorest.
One in five Filipinos lives in deep poverty, and a majority of the population can barely make ends meet with their salaries.
Among those in the audience on Friday who heard the Pope's message was former president Joseph Estrada, who is now mayor of the capital Manila.
Mr Estrada was convicted of plunder in 2007 and sentenced to life imprisonment, but he was pardoned that same year by his predecessor, Mrs Gloria Arroyo.
Mrs Arroyo herself is now facing graft charges filed against her after her term ended. She has been under hospital arrest since 2012 for allegedly conspiring to divert 366 million pesos (S$10.9 million) in charity funds to her own accounts.
President Benigno Aquino won power in 2010 with a pledge to rid the country of its image as one of the most corrupt in Asia.
Ranked 134th out of 178 nations and territories in Transparency International's 2010 corruption perceptions index, the Philippines improved to 94 in 2013 from 105 in 2012.
Allegations that the government misappropriated state funds in its stimulus plan, as well as misuse by some lawmakers of a 10-billion-peso discretionary fund, have threatened to tarnish Mr Aquino's anti-corruption credentials.
In his speech, the Pope also underscored the Philippines' "important role in fostering understanding and cooperation among countries in Asia".
The Philippines - with its 80 million fervent Catholics - is seen as a key launchpad as the Vatican seeks to broaden its influence in a continent where only 3 per cent of a 4 billion-strong population are Catholics.
Pope Francis, an Argentinean, has made Asia a new priority, with two visits in less than six months, moderating a more Eurocentric vision of the church that has prevailed in recent years.
Another issue that the Holy See hammered on is labour migration, expressing specific concern over the "Filipinos of diaspora". One in 10 Filipinos live abroad, with 180,000 of them in Singapore.
Their remittances has helped buoy the Philippine economy, but it has also taken a huge toll on families, with parents alienated from their children and couples breaking up.
Later on Friday, Pope Francis attended a rally of families at Manila's top concert arena. He broke protocol when he went across the street after the mass for a surprise visit to a church-run home that cares for street children, many of whom were once child prostitutes.