Congratulations to thousands of volunteers who contribute their energy and initiative to projects around the world, including critical United Nations activities, senior UN officials offered yesterday as they marked the day dedicated to those who give their time and efforts for free to help others.

"The altruistic spirit of volunteerism is immense and renewable," Secretary-General Ban Ki-moon said in a message released for International Volunteer Day, which has been observed by the UN and civil society on December 5th every year since 1986.

Around the world volunteers are holding events this week to mark the Day: in Haiti, a school damaged by hurricanes is being rehabilitated; in Sudan, doctors and dentists are providing free medical consultations; in Kazakhstan, children in orphanages and hospitals are receiving "clown therapy"; and in Indonesia, new mangroves are being planted.

UN Volunteers (UNV) deploys about 7,500 people in 140 countries every year to support national development efforts.

Yesterday UNV launched an online volunteering service – which brings together hundreds of development organizations and thousands of volunteers who would otherwise have time or physical constraints from participating – in French and Spanish and re-launching an upgraded version in English.

"Online volunteers have contributed to environmental projects in Africa, human rights in Asia, youth education in Latin America, and community work worldwide," Ms. Pansieri said in a statement.

"Online volunteering promotes social inclusion and contributes in a very tangible way to the work of development organizations and communities facing some of the toughest challenges of our time."

UNV volunteers often work closely with the UN Development Program (UNDP), and that agency's Administrator Kemal Dervis highlighted their joint efforts to improve conditions in countries emerging from disaster or conflict by rebuilding infrastructure, promoting democratic governance and engaging marginalized or vulnerable groups, such as women and youth.