Ceremonies and protests have marked Chad's official entry as the world's newest oil-producing country.
With a ceremony attended by hundreds of dignitaries and thousands of onlookers, Chad Friday opened a symbolic spigot to inaugurate its oil field in the southern Doba.
Four heads of state from other African oil-producing countries were on hand, as the ceremony began about 90 minutes late on Friday.
Last week, a first tanker carrying nearly 1 million barrels of Chadian crude left a port in Cameroon. The oil was pumped to the port oil terminal through a pipeline that covers more than 1,000 kilometers.
The World Bank funded part of the pipeline. Chad is expected to make more than $2 billion over the next 25 years, and Cameroon another $500 million.
The oil revenue is expected to double Chad's foreign income.
But some civic groups in Chad observed what they called a "day of mourning" Friday, saying the oil revenue will strengthen the oppressive government, but is unlikely to benefit the seven million ordinary Chadians.
Civic groups say Chad's population, one of the world's poorest, is a victim of frequent human rights violations, insecurity and deteriorating public services.
In a plan approved by the World Bank, Chad's government has agreed to open the books on spending the oil revenues to public scrutiny. Under the World Bank plan, most of the money is to be spent on health, education and infrastructure.
American human rights campaigner, Ian Gary, the author of a report on oil wealth, called The Paradox of Plenty, says countries importing African oil and multinational oil companies must also be held accountable.
"We are urging the U.S. government in its bilateral relations with countries like Chad to emphasize respect for human rights, democratic institutions and transparency over the management of oil revenues," he said. "When it comes to the international oil companies, we believe that the most important thing that they can do is publishing what they pay African governments, that's the revenues, the taxes and any kind of royalties that oil companies pay national governments. These need to be transparent. It's awfully hard for local civil society groups to hold their own governments to account on how oil money is spent when they don't even know the figures involved."
There are also fears about the impact on the environment. Wells, power stations and landing strips are being built in southern Chad, the country's farming region.
In Cameroon, the concern is over the effect the pipeline leading to the Atlantic Ocean will have on rainforests and Pygmy populations.