A toddler's cries ring out in a paediatric ward where about 20 children lie emaciated from malnutrition in this northern Mali town, whose occupation by Islamists has caused a humanitarian crisis.

"He is suffering from chronic malnutrition," says chief nurse Ibrahim Maiga of the crying three-year-old, pointing out other children suffering from acute malnutrition, and others receiving special nutritional treatment after nearly dying.

Gao, like the rest of northern Mali, has been occupied by Al-Qaeda-linked Islamists since late March, cutting the region off from the south and the capital Bamako.

The arid north is already suffering a food crisis along with the rest of the Sahel region, which has millions going hungry after poor rains last year.

Food supplies are either brought in on charter flights by charities and the Malian Islamic High Council, or are smuggled in from neighbouring countries such as Algeria and Niger and sold tax-free in the main cities of Gao, Kidal and Timbuktu.

Algeria, Morocco and Qatar have also given food aid.

But some residents of the region fear their new Islamist rulers will co-opt the aid to advance their own agenda.

"The problem arises with the distribution of the aid. The Islamists, masters of the region, cannot be ignored," an accountant in the region said on condition of anonymity.

"The risk is that they make the distribution of supplies a formidable weapon" and reserve them for those who support them.

Aside from the food shortage, poor sanitary conditions have increased the risk of epidemics such as cholera, which has broken out in northern Mali and other parts of the Sahel.

At the Gao hospital, Alzatou Maiga, who is weighing the children as they arrive, told AFP that three children have died in two months from malnutrition.

"We live in solidarity and those who have a little share the little that they have," said a teacher in the town.

The chief nurse Ibrahima Maiga said it was difficult to evaluate what was happening outside of Gao, a town in the north-east of Mali not far from the Niger border.

"Because of the problem of insecurity we can't go into the region, so the sick are forced to make a plan to get to Gao."

A woman at the hospital has brought her child, who is so weak he cannot get up. She explains that her husband is a farmer, but because of the various crises is no longer able to cultivate his fields.

"We don't have anything to eat today, we don't know what we are going to do," she says.

The vast northern triangle of the bow-tie shaped nation was seized by Islamist and Tuareg rebels in the chaos following a military coup in Bamako on March 22.

Since then the Islamists have chased out the Tuareg and exerted their control on a desert region larger than France, implementing strict Islamic law and destroying ancient World Heritage shrines they consider idolatrous.

Over 365,000 Malians have fled their homes, about 250,000 of them to neighbouring countries, increasing the pressure from the food crisis in the region.

"The humanitarian situation can become even more difficult. All aid needs to be urgently coordinated," said Djite Moulaye, president of a committee managing humanitarian action in Gao.

The cholera epidemic has been brought under control for the moment after two people died in a village near Gao, according to the International Committee of the Red Cross.

"That is lucky, otherwise it would have added one catastrophe to another catastrophe," said Alima Toure of Doctors of the World, whose main concern is organising visits to the most isolated regions to "avoid the worst".

While they themselves are struggling to survive, the residents of northern Mali are also trying to help their relatives who have fled.

"The aid from the international community is not sufficient and our relatives are asking us to send them a little money again," said Abdoulaye Bachily, a member of the Islamic High Council in Gao.

After the occupation and atrocities committed by the armed groups in the region, the drought, hunger and cholera outbreak, Mali is also facing a locust plague after heavy rains this year.

"I ask myself if Mali has not been cursed," said youth Ismael Guindo.