"At a time of multiple global crises, the poorest and most vulnerable have a special claim on our attention," he said in a message. "We know that, in any recession, those hurt first - and worst- are the poor."

He noted that according to recent estimates, the global economic crisis has claimed at least 50 million jobs this year and up to 100 million more people are expected to fall below the poverty line in 2009. Climate change further compounds the problem.

"Now is the time to amplify the voices of the vulnerable and ensure that the world follows up on its pledges," he said. "With the right investments and concrete action, we can build upon the gains, fulfil our commitments, and ensure that every man, woman and child has the opportunity to make the most of their potential."

The Day's theme this year is "Children and Families Speak Out against Poverty," and UN Children's Fund (UNICEF) Executive Director Ann M. Veneman highlighted the harm that poverty and its concomitant ills of malnutrition and lack of education inflict on the young.

"Early childhood, in particular, lays the foundation for a lifetime. Children who are chronically undernourished before their second birthday are likely to have diminished cognitive and physical development for the rest of their lives," she said in a message.

"Investing in better nutrition for children helps improve their lives and contributes to the development of their communities. Research shows that every dollar spent on vitamin A and zinc supplementation for children creates benefits that exceed $17.

Noting the importance of investment in education, she cited experts' estimate that one dollar invested in girls' education provided a ten-fold return in increased productivity.

"Studies also show that educated adolescents are more likely to wait until they are out of their high-risk teenage years before starting a family and have healthier babies," she said.

The UN Independent Expert on human rights and extreme poverty, Magdalena Sepúlveda, stressed that 2009 has been one of record job losses, with malnutrition expected to reach a historic peak of over 1 billion people and tightening budget constraints threatening investment in education and health care.

"The crisis is not over," she said in a statement. "In fact, its full impact, particularly on the most vulnerable, is still unfolding. From a human rights perspective, we are far from a recovery on the contrary, poverty and hunger are still increasing."

Echoing those comments, UN human rights chief Navi Pillay noted that although economists are now seeing signs of recovery, it is likely to have little if any impact on the daily lives of many millions of the world's poorest people for a long time to come.

"The prosperity of our society tomorrow depends to a considerable degree on the situation of our children today," she said. "Children of poor families are amongst the hardest hit in times of economic crisis, and the lack of social protection measures will have lifelong consequences for them, and for the societies in which they live."

Meanwhile, Helen Clark, the head of the UN Development Programme (UNDP), used her message for the Day to call for action to tackle the impoverishment associated with climate disasters in the developing world.

"Efforts to eradicate poverty and to tackle climate change cannot be separated," she stated, noting that the effects of climate change weigh disproportionately on the poorest, and on women and children. She called on countries to reach a climate change deal this December in Copenhagen that is "positive for our climate and for poverty reduction and development."

As this year's Day falls on a weekend, the UN will be holding a full programme of activities at UN Headquarters in New York on Monday, coinciding with the observance of the 20th anniversary of the Convention on the Rights of the Child.

These will include testimonies from children and families living in poverty and an interactive panel discussion on the theme "Children: the future and present - participation in poverty reduction and the accountability for rights."

Yesterday Mr. Ban used a visit to the UN International School (UNIS) in New York to rally children in the battle against extreme poverty, inviting his youthful listeners to first crouch and then rise in a symbolic gesture of the UN's "Stand Up Against Poverty" campaign.