Chad has declared a food emergency due to lack of grain supplies, caused by the war in Ukraine.
The government said the food situation had deteriorated significantly since the beginning of the year, and international humanitarian aid was needed urgently.
According to the UN, 5.5 million people in Chad, a third of the population will be in need of food aid this year.
African Union President Macky Sall, is due to meet Russian President Vladimir Putin in Sochi on Friday, to call for a lifting of the export blockade on grain and fertiliser.
Ukraine and Russia are the world’s biggest wheat exporters.
The UN said 54 African countries import nearly half of their wheat from Ukraine and Russia.
Russia is also a major supplier of fertiliser to a dozen African countries.
Chad is one of many countries in the Sahel facing a hunger crisis.
Ethiopia, Kenya, Sudan and Somalia, are facing their worst drought in 40 years.
The UN also said West Africa was facing its worst food crisis in a decade.
According to aid agencies, 60 million people may soon face starvation in the entire Sahel region.