At least 44 people have been killed by severe flooding that has affected Niger since mid-July, the UN's humanitarian affairs office said Thursday, while scores of thousands are homeless.

Though floods have struck all regions of the west African country, half of the 44 deaths registered by August 22 were in the region of Maradi, the economic capital in the southeast, according to the Office for the Coordination of Humanitarian Affairs (OCHA) branch in the capital Niamey.

The previous UN toll was 31 dead.

Half of the victims drowned and the others were killed when their homes collapsed. Five people died in Niamey, where the Niger river overflowed its banks, and five others in Zinder.

After visiting some of the affected areas on Monday, President Mahamadou Issou pledged 1,400 tonnes of food and 900,000 euros ($1.1 million) in aid but admitted it would not be enough.

"That will not suffice. I am calling on our partners to help us overcome this difficult situation," he said.

OCHA counted 176,000 people hit by the floods. However, Interior Minister Abdou Labo on Wednesday said that "more than 340,000" people were directly affected and announced that the government had released emergency aid worth 200 million CFA francs (304,000 euros) out of the pledged amount.

Labo reiterated the plea for international assistance.

Opposition leader Seini Oumarou has criticised government "inertia" in handing out aid.

More than 14,000 homes have collapsed across the country and 7,000 fields of cereal crops have been destroyed, according to OCHA.

Most of the homeless are being put up in schools and public buildings or by relatives.

The southern Dosso region is among the worst affected in the land-locked country, OCHA warned earlier in the week, with nearly 70,000 displaced people and three deaths last week.

OCHA said that flooding will have "a negative effect on the food situation" in Niger, which straddles the semi-arid Sahel belt running across Africa, separating Sahara from savannah.

Millions of people are going hungry in the region after crops failed across a swathe of eight countries because of late and erratic rains last year.