Officials say the death toll could climb after militants, who arrived on motorbikes and in cars, attacked a military base in the Gao region.
Nigeria's military said attacks by militants from Boko Haram and a splinter group affiliated with Daesh had "necessitated the contiguous nations of the Lake Chad basin to jointly launch this massive onslaught."
"It's the first time we have lost so many men," President Idriss Deby Itno says, after visiting attack site in Lac province, which borders Niger and Nigeria.
Insurgents fired rocket-propelled grenades at a lorry carrying troops as it travelled near Gorgi village in Borno state, two military officers said without giving their names.
Local sources said a "major" attack had killed soldiers who were hospitalised in Diffa, but they did not give figures.
A stampede was triggered during the distribution of food and money, $13.75 per person, in Diffa, the main town of a southwest region of that name that abuts Nigeria and Chad.
Militants targeted the village of Auno on a key highway linking to regional capital Maiduguri, officials say, adding many women and children were abducted in the raid.
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A woman set off explosives in a crowd in Kaiga-Kindjiria, a town that has been attacked by Boko Haram militants in the past.
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"Heavily-armed terrorists" target convoy in western region of Tillaberi, killing seven police personnel and seven national guards, interior ministry says.
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