Benin forces suffered heavy losses in an attack near the border between insurgency-hit Niger and Burkina Faso, authorities said.
National Guard Chief of Staff Colonel Faizou Gomina said the north hit one of Benin's best-equipped military positions on Wednesday evening.
“We have been hit very hard,” added Colonel Gomina.
The country has witnessed increasing attacks in the north in recent years blamed on jihadist groups based in neighboring countries
More than 120 Beninese military officers were killed between 2021 and December 2024, a diplomatic source told AFP news agency.
Last month, gunmen killed three soldiers and wounded four others guarding an oil pipeline in the northeast.
Colonel Gomina did not provide a death toll for Wednesday's attack, but the main opposition party, the Democrats, said about 30 soldiers were killed in the Alibori region, Reuters news agency reported.
A security source put the death toll at 28, AFP reported.
“We are continuing the clean-up operation. Forty attackers have been neutralized so far,” the military source added.
Colonel Gomina said the attacked position was “one of the strongest and most militarized” and called on military commanders to improve their operational tactics to counter the security threat.
“Wake up officers and department heads, we have a fight to win,” he said.
In 2022, Benin deployed around 3,000 troops to prevent cross-border infiltration and strengthen security in the north.