obligation on countries to register every child immediately after birth. Sixteen years later, every country in the world has ratified the convention except the United States and Somalia.

"It is, in a very real sense, a matter of life and death," the South African Nobel Peace Prize winner said. "The unregistered child is a nonentity. The unregistered child does not exist. How can we live with the knowledge that we could have made a difference?"

But according to the latest UNICEF (news - web sites) figures, over 48 million births each year — 36 percent of births worldwide — are not registered, the vast majority in developing countries.

Plan, the British aid agency, released a 50-page report titled "Universal Birth Registration — a Universal Responsibility" to coincide with the campaign, which is backed by UNICEF. The British agency said it is impossible to know how many unregistered children there are because they cannot be counted, but best estimates put the number at more than 500 million.

Tutu told a news conference that a birth document "proves who you are" and without one children and adults are often barred from education, health care, citizenship and the right to vote.

"Governments worldwide are failing the world's children, as millions of youngsters without a birth certificate find it very difficult to prove their age or nationality," said Thomas J. Miller, former U.S. ambassador to Greece and Plan's new chief executive.

"And parents whose children go missing, during disasters like the tsunami or because they are abducted by traffickers, may even be unable to get help with tracing their sons or daughters because they cannot prove the age of their children — or in many cases that their children even exist," he said.

The region with the most unregistered children is south Asia with 63 percent of births not recorded every year, followed by sub-Saharan Africa with 55 percent. In central and eastern European countries and the former Soviet bloc, 23 percent of children aren't legally registered; in east Asia and the Pacific 19 percent; in the Middle East and North Africa 16 percent; in Latin America and the Caribbean 15 percent; and in industrialized countries 2 percent.

Miller blamed neglect and apathy among governments for the failure to register children.

"This is not high technology and it's not expensive," he said, noting that in Cambodia, which he just visited, 2.4 million people were registered in less than four months using fingerprints.

Philippines Senator Companera Pia Cayetano said her country was aiming for 100 percent birth registration by 2010 and called for the lowering or elimination of registration fees.

Plan is currently working with local partners in over 40 countries to boost the rates of child registration, Miller said.

"This is going to be a work in progress for the rest of our lives," he said.

Tutu urged those who successfully fought for an end to apartheid to join the campaign to ensure that every child in the world is registered and has an identity.

"I never give up," he said. "I believe human beings are fundamentally good and that when people want to do good, they will do the right thing."

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