Nigeria's worst flooding in decades has submerged houses and displaced hundreds of thousands of people, so Gibson Orlu was shocked when authorities at a relief camp told him to return home.

"To where?" the 54-year-old told a reporter when recounting the exchange later at a crowded and rudimentary relief camp in the southern state of Bayelsa, where authorities have stopped providing food to the displaced.

"I have nowhere to go. My house is gone."

According to estimates from Nigerian authorities, surging waters this rainy season in Africa's most populous nation have killed at least 363 people and left another 2.1 million homeless.

The flooding also slashed crude production by about 20 percent for a period in a country that is home to the continent's largest oil industry.

Red Cross figures released so far on deaths and the displaced are much lower than Nigeria's, but the relief organisation still says the flooding has been the country's worst in four decades and has appealed for funding to help.

The flood waters have now largely receded as the rainy season comes to a close, but vast areas throughout Africa's most populous nation had been inundated.

Some of the worst flooding was in the oil-producing Niger Delta region, the central state of Kogi and the northeastern state of Adamawa.

President Goodluck Jonathan's private home was submerged in the Delta's state of Bayelsa. Some of the state's residents, including Orlu, said they feared being left with nowhere to stay.

"My wife and three children are squatting with my brother in Port Harcourt. The kids are out of school because of this problem and now they are asking me to leave," he said.

Inside the camp at a sports complex where he was staying, some slept on mattresses while others were on the bare floor. Several hundred people were there when an AFP journalist visited last week, and some asked for change so they could buy food.

Other camps are outdoors, with the displaced sleeping under tents.

Relief workers insisted that the camps were set up as temporary solutions, using borrowed land.

"They have to leave whether they like it or not because this complex has to be used as a training venue for the state contingent to this year's national sports festival," said Nikki Maweruya, the camp coordinator at the sports complex in Yenagoa, the capital of Bayelsa state.

On November 15, officials announced that all camps in the state were to be closed in part because the facilities being used as temporary shelters, including classrooms, were needed for their regular purpose.

At the sports complex in Yenagoa, Maweruya said buses had been hired to carry camp residents back to their villages.

"But many of them are not willing to leave," he explained.

While the water has receded in many parts of the state, many homes have been left uninhabitable, with pools of water still standing in the ground floor.

In an October speech broadcast nationwide on all major TV channels, Jonathan called the flood damage "unprecedented" and pledged $110 million in aid to those affected.

The UN humanitarian agency said earlier this month that flood damaged areas are facing severe food insecurity and there is a serious risk that water-borne diseases, including cholera, could spread.

A volunteer at the Bayelsa camp, Elizabeth Egbe, said forcing people to return to unliveable communities could dangerously unsettle the area.

The region could see a spike in crime, she argued, as the farmlands that provide a key source of income for many have been destroyed on a massive scale.

"Society will be chaotic," she told AFP.

Nigeria has suffered similar tragedies in the past. Last year, 102 people were killed in Ibadan in southwestern Nigeria following flooding.

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

An 87-year-old grandmother from Bayelsa state's Sagbama area, Lydia Anuasa, said this year's rains nearly killed her.

"It had been raining for several hours and I was fast asleep when the floods came," she explained as she held court amid a group of frustrated camp residents.

"Before I realised what was happening the whole place had been flooded. It was my neighbours who saved my life. They carried me out of the house."

Still full of vigor despite her years, Anuasa said she was among those with nowhere to go and needed more government help as her house was still under water.

"I can't go back to that place now."