ADDIS ABABA, May 25 (Xinhua) -- The celebrations to mark the 50th anniversary of the Africa Union (AU), the successor of the Organisation of African Unity (OAU), have kicked off in the Ethiopian capital city of Addis Ababa Saturday, amid rising optimism over Africa's future.

Zambian President Michael Sata said in the last 50 years, most African countries managed to achieve valuable progress in their national development, including achieving higher economic growth rates.

"Addis Ababa was not what it is today 50 years ago," President Sata told journalists a day before world leaders joined the leadership of the AU to hold the commemoration of the continental Jubilee.

Amid challenges to peace and stability in Africa, leaders believed progress several fronts in Africa remained vibrant.

"We should be proud of Africa," said Dr Mustapha Sidiki Kaloko, the AU Commissioner for Social Affairs.

African leaders, who gathered here to usher in yearlong celebrations, are insisting on propelling the voice of Africa to a more prominent role in the international scene.

"We have an Africa that is growing, more self-confident and playing a greater role on the global scene. In other words, we are on the cusp of an African renaissance," said Carlos Lopes, head of the UN Economic Commission for Africa (ECA).

At the Summit, leaders are being nudged to reflect on the economic progress that is attainable in all areas of national development to achieve the dream of a progressive region of the world.

Lopes said while discussing elements of unity, culture and freedom of the African people, measures were required to assert the voice of ordinary citizens in talks about the future of Africa.

The celebrations being marked here have been styled to honor veterans for Africa's struggle against colonial rule.

"We need to move away from the quantitative valuation to qualitative valuation of what has been achieved in education and healthcare," said Binyam Dawit Mezmur, an Ethiopian Assistant Professor, speaking here as Chairperson of the AU Committee of Experts on the Welfare of the Child.

The Committee has warned that despite good progress in combating harmful traditional practices that limit the progress of African children, more still needed to be done to create a better world.

"We are talking about concrete progress in 50 years, the number of mothers dying while giving birth have been reduced, more children are accessing education and human rights has been improved," Binyam said.