Cloudbursts that began to pound much of the southern belt of the arid country where nomads graze cattle and farmers plant fields of millet have raised hopes of a decent harvest.

"This year we think it's going to be alright, rain's falling from time to time," said maize grower Issa Chaibou, 28, washing his bicycle in a large pond. "If the rain continues like this it's going to be better than last year."

But aid trucks rumbling more than 550 km (340 miles) by road from the capital Niamey will find it impossible to access many of the hungriest villages linked to the northeastern town of Tahoua by tracks that dissolve into mud during downpours.

"Rain is good for the country but it can also hamper deliveries," said Anita McCabe, spokeswoman for Dublin-based aid agency Concern, which plans to distribute food in the village of Barmou outside Tahoua on Monday.

"If it rains a lot it will be difficult to get to the sites. We have heavy trucks travelling to the sites and they may actually damage the roads if they're too heavy, so we need to make several journeys," she said.

For inhabitants of villages moulded of mud, prayed-for rain can have unpleasant side effects.

In the settlement of Madoufa outside Tahoua residents pointed to the walls of huts built of earth and stone that collapsed during a storm over the weekend, saying some of their newly-planted crops had also been swept away.

"Walls fell down and the water washed away the millet," said Hussein Lowaly, 25. "It affects lots of fields."

Delays due to rain are just one factor that could push up the costs of averting mass starvation in Niger, where relief workers say a late response by international donors and aid agencies has made saving lives much more expensive.

Food that could have been sent by truck months ago is now being flown in at much higher cost in cargo planes, while children who were merely hungry earlier this year are now sliding towards critical levels of malnutrition.