UNITED NATIONS - Top UN officials on Wednesday urged the Group of 77 plus China to work collectively towards reaching the anti-poverty targets known as the Millennium Development Goals (MDGs) by the 2015 deadline.

During his remarks at a ceremony at the UN Headquarters where Fiji handed over the chairmanship of the Group to Bolivia, UN Secretary-General Ban Ki-moon called for "greater ambition and increased action on the ground."

"Less than two years remain to the end of 2015," said Ban. "In that time, we must do much more to achieve the MDGs, define a unified and universal post-2015 development agenda and agree on a global climate agreement."

He noted the importance of the group's members working together with the available tools to eradicate poverty and improve social and economic well-being.

The UN chief also lauded the role of the G77 and China in achieving sustainable future, saying the group represents the "aspirations of billions of the world's least privileged people."

"We will all benefit from your unity, your collective progress and your combined contribution to achieving a sustainable future for all humankind," he added.

UN General Assembly President John Ashe also stressed the importance of laying the groundwork for a post-2015 development agenda.

"The next 12 months will determine whether or not we are able to deliver on the promises of 2015," he told participants at Wednesday's event, where Bolivian President Evo Morales replaced the outgoing G77 Chairman Ratu Inoke Kubuabola, whose one-year term expired in December 2013. Ratu Inoke Kubuabola also serves as Fiji's Foreign Minister.

In commemorating the 50th anniversary of founding of the Group, Ashe praised the Group for its strong commitment to working together over the years, even as goals and national circumstances have changed.

"You are an example of the might of South-South cooperation, and a harbinger of greater collaboration that is yet to come," said Ashe.

The Group, established in 1964, is now a coalition of more than 130 developing UN member states plus China, and has more than 60 percent of the world's population.

The Group is the largest intergovernmental organization of developing countries in the United Nations, aiming to promote collective economic interests and gain leverage within the international community. ?

The chairmanship, which sits atop the organizational structure of G77, rotates on a regional basis (between Africa, Asia-Pacific and Latin America and the Caribbean) and is held for one year only.