The flooding began suddenly when the gates on the Challawa and Tiga dams were opened, a spokesman for the Jigawa governor said.

"We have about two million people affected," Umar Kyari spokesperson of Jigawa state told AFP. Jigawa has a population of about 4.3 million people.

"When the rains became too much they realised the water was too much and opened the dams," he said.

About 90 000 hectares of farmland were washed away with food and livestock estimated at 4.5 billion naira destroyed.

"Over 5 000 villages in 11 of our 27 local government areas were affected. It started more than two months ago and it's continuing as I speak," he said.

The displaced have moved to higher and dry areas where they are sheltering in schools.

Kyari said that although the gates are opened almost every year to avoid overflowing and waters wash away villages on the low-lying plains of the state, "this year is just very bad".

"This year is so, so devastating," he said speaking by telephone from Dutse, the capital of Jigawa state.

Several other states in northern Nigeria have been hit by floods this year.

The floods came despite forecasts of low rainfall in the north for this year's rainy season from Nigeria's meteorological agency, which had previously warned that more than 12 million people in the region could face food shortages as a result.