At least 17 soldiers and 36 volunteer fighters have been killed in heavy clashes with militants in northern Burkina Faso, the army said.
Seventeen soldiers and 36 civilian volunteers for the army died on Monday while repelling an "attack," the army general staff said in a statement.
The Economic Community of West African States (ECOWAS) condemned the attack.
The regional bloc said in a statement that it was "shocked" by the deaths of soldiers and civilian volunteers, deploring the "terrorist attacks" and expressing "solidarity with the people of Burkina Faso".
Burkina Faso was suspended from ECOWAS after the army seized power.
The violence in Burkina Faso carried out by armed groups linked to al-Qaeda and the terrorist organization ISIS, which the country has been witnessing since 2015, has led to the displacement of more than two million people inside the country.
Terrorist groups are also active in two countries bordering Burkina Faso - Mali and Niger, which are also governed by military personnel - which have witnessed two coups since 2020.