An overcrowded boat capsized Monday in Congo, witnesses said, leaving at least 106 people missing in the latest transportation tragedy in this vast Central African country of jungles and huge rivers.

The boat carrying passengers and merchandise sank on the Kasai River in Kasai-Occidental province, according to local resident Vickie Ndaye. The mayor of the town in south-central Congo where it happened confirmed the disaster but did not immediately offer any further details.

Another boat capsized last year on that same river, a tributary of the Congo River, leaving as many as 200 people dead. Investigators later said there were four times as many people onboard that vessel as the passenger list claimed, and that the boat operators bribed officials to allow them to overload it.

Congo suffered back-to-back civil wars beginning in the late 1990s and today has only 600 miles (1,000 kilometers) of paved roads in a country the size of Western Europe.

The Congo River is the only real highway in the vast country. Barges traverse the river like floating villages crowded with up to 2,000 people, mainly traders and their goods, from bags of sorghum to barrels of palm oil.

It can take weeks to get from the river's source in the south to Kinshasa, the capital, meandering in a scythe-like arc. The river is nearly 3,000 miles (4,800 kilometers) long and about 10 miles (16 kilometers) wide at some points.

Since barely anyone can afford to fly, travelers in Congo ride on boats and barges not intended for people even if they do not know how to swim, sleeping at night next to sacks of maize and piles of timber amid the stench of fish. The boats are often in poor repair and filled beyond capacity, and the industry is not well-regulated.

Authorities said at least 72 people were missing after a boat capsized on a lake in eastern Congo a week ago.