At least 26 children aged between 5 and 6 were killed in flames on Monday when their straw and wood classrooms caught fire in southern Niger.

"Right now, we have 26 dead and 13 injured, four of them seriously," said Chaibou Aboubacar, mayor of Maradi City.

Three days of mourning have been declared in the Maradi region from Tuesday.

"This tragic event once again puts the Nigerien people in mourning," the government said in a statement, adding that straw and wood classrooms would henceforth be banned across the country. 

"For the moment we cannot state the origin of the fire," regional director of education Maman Hdi said.

It was the second time this year that a fire has killed pupils in their classrooms in the West African country. Twenty preschool children were killed in April fire in Niamey.

(With input from Reuters, AFP)