Authorities arrested the migrants as they attempted to cross into Algeria in a convoy of five vehicles, officials said Saturday. The migrants, who included 18 Nigerians, were taken to the northern town of Arlit.

"The migrants were mostly men with a few children. They were arrested in the desert and are being held in Arlit, the town from where they illegally left for Algeria," a security official who wished to remain anonymous said.

"The migrants are being held at the gendarmerie but we do not yet know what will become of them," another source said.

The latest figure came a day after Niger's government announced it had "intercepted" 47 migrants headed for Assamaka, the last town in Niger on the route to Tamanrasset, in southern Algeria on Friday. It also said it was ordering the immediate closure of migrant camps used by migrants in the north of the country, vowing that those involved in human trafficking would be "severely punished."

The renewed effort to clamp down on illegal migration and trafficking networks follows the discovery on Wednesday of 92 bodies. The victims, mostly women and children, perished attempting to make the same desert journey.

They reportedly died of thirst in early October after they were left stranded in the desert when their trucks broke down.

The group was thought to have been travelling across the Sahara on their way to Europe.

The UN's Office for the Coordination of Humanitarian Affairs estimates that at least 30,000 economic migrants passed through Agadez, northern Niger's largest city, between March and August of this year.

The UN ranks Niger as the least developed country on earth.

ccp/hc (AFP, Reuters)