Flooding in eastern Nigeria has killed at least 10 people and displaced an estimated 20,000 following heavy rains and the release of water from a dam in neighbouring Cameroon, an official said Monday.

"The flooding swept away more than 40 villages and killed at least 10 people while many others are still missing," said Shadrach Daniel, head of the emergency management agency in Nigeria's Adamawa state, where the flooding occurred.

"There are now around 20,000 displaced people sheltering in temporary camps who are in dire need of basic provisions like food, water, clothing and blankets."

He said water was released from the Lagdo dam on Friday in neighbouring Cameroon after officials there warned Nigeria several weeks ago. The opening of the dam led to flooding along the Benue River in Nigeria.

"The people along the Benue River were advised to leave but did not heed the warning," he said.

"Thousands of hectares of crops and homes were destroyed in the flooding. We have started a situation assessment to see how best we can assist the affected people."

Flooding this rainy season in various parts of Nigeria, Africa's most populous nation with some 160 million people, had already killed dozens. Much of the country has been affected by heavy seasonal rainfall.

The toll includes more than 60 people left dead in two separate floods in Plateau state in the country's centre.

In July, at least three people were killed by flood waters some 150 kilometres (90 miles) north of the economic capital Lagos in Ibadan, an area of southwestern Nigeria where 102 died following torrential rains last year.

At least 20 people died from flooding in Lagos last year, while 24 were killed after rains inundated a neighbourhood in Nigeria's largest northern city of Kano.

Nigeria's disaster management agency has warned that 12 of the country's 36 states would experience flooding this rainy season, which typically runs from March to September.

The largest cities in Nigeria are overcrowded, with many residents living in haphazardly constructed slums. Drainage systems are also often poorly maintained and contribute to the problem.

In 2010, flooding affected roughly half a million people in two-thirds of Nigeria's 36 states.

Seasonal flooding also affects the west African region, with 2010 having been a particularly harsh year.

More than 300 people were killed in the 2010 rainy season in western and central Africa and at least 680,000 people were affected by the floods in neighbouring Benin, a country of some nine million.

The flooding also raises the risk of the spread of diseases such as cholera.