Eleven soldiers were killed and nine reported "missing" on Friday following a jihadist attack on an army position in Dagne in western Niger, days after 69 civilians died in an ambush, the government said.
The attack by "a column of heavily armed terrorists in several vehicles and dozens of motorcycles" killed 11 soldiers, and left one injured, according to a statement from the Ministry of Defence read on public television.
"After fierce fighting, the enemy column was forced to retreat with its dead and wounded," added the statement, which said "air and ground reinforcements dispatched to the area continue to sweep" the locality.
The soldiers targeted had been deployed to ensure the safety of the thousands of villagers who had returned to their communities after the earlier killings.
At least 69 people, including a local mayor, died earlier this week in an attack in the country's volatile "tri-border" zone with Burkina Faso and Mali.
The assault took place on Tuesday at Adab-Dab, a village about 55 kilometres (32 miles) from Banibangou in the western region of Tillaberi, but was only confirmed by the government on Thursday.
The government declared two days of national morning from Friday.
Local sources said a motorcycle-borne defence force was attacked by "heavily armed members of the ISGS (Islamic State in the Greater Sahara," who were also on motorbikes.
Another source said the target of the attack on Tuesday was a local anti- jihadist defence force called the Vigilance Committees, which was headed by the mayor of Banibangou district.
The defence force had recently been set up by local people following a string of attacks on farm workers in remote fields by highly mobile jihadists, a former mayor said.
The world's poorest country by the benchmark of the UN's Human Development Index (HDI), Niger is facing jihadist insurgencies both on its western border with Mali and Burkina Faso and on its southeastern frontier with Nigeria.
The western insurgency began with incursions in 2015. The bloodshed escalated in 2017, with massacres carried out by groups affiliated to al- Qaeda and the so-called Islamic State.
Human Rights Watch estimated in August that more than 420 civilians had been killed since the start of the year in western Niger. In one incident alone, 100 people were killed in attacks on villages on January 2.
In March, 141 members of the Tuareg community were massacred in Tahoua, a vast desert region abutting Mali.