Niger began three days of national mourning Tuesday after 29 soldiers were killed in a suspected jihadist attack, the deadliest since the military took power in July.
The latest violence comes as the country's coup leaders indicated they were considering neighbouring Algeria's offer to mediate talks for a transition back to civilian rule.
Niger is battling two jihadist insurgencies -- a spillover in its southeast from a long-running conflict in neighbouring Nigeria, and an offensive in the west by militants crossing from Mali and Burkina Faso.
When military leaders overthrew democratically elected president Mohamed Bazoum on July 26, they cited the deterioration of the security situation in the country as justification.
Monday's attack in western Niger involved "improvised explosive devices and kamikaze vehicles by more than a hundred terrorists", the Ministry of Defence said in a televised statement.
It added that two soldiers were seriously wounded and "several dozen terrorists" were also killed.
The attack took place northwest of Tabatol near the border with Mali, which is plagued by fighting with militants affiliated with the Islamic State group and Al-Qaeda.
Violence in the "three borders" area between Niger, Mali and Burkina Faso has fuelled military takeovers in all three countries since 2021.
Algeria, Niger's influential neighbour, said on Monday that Niamey has accepted its offer to mediate talks on a transition to civilian rule.
Hours later, Niger's Ministry of Foreign Affairs said it had "indicated the availability of the Nigerien authorities to examine Algeria's offer of mediation".
- Transition period -
Niger's military leader, General Abdourahamane Tiani, has previously said he wants a transition of no more than three years.
In August, Algeria proposed a six-month transition plan under the supervision of a "civilian authority led by a consensual figure accepted by all sides of the political class".
Algiers made no mention of an exact timeframe in its statement on Monday but said Foreign Minister Ahmed Attaf would visit Niamey "as soon as possible with the aim of launching discussions... with all stakeholders".
In response, Niger's military leaders said the duration of any transitional period was to be decided by an "inclusive national forum".
Since Niger's coup, the deposed Bazoum has been held in his presidential residence with his wife and son.
On Monday, his lawyers said they filed a lawsuit against the coup leaders.
The complaint, seen by AFP, targets General Tiani and "all others", and alleges "attack and conspiracy against state authority, crimes and offences committed by civil servants and arbitrary arrests and confinements".
His lawyers also said they were appealing to two bodies of the UN Human Rights Council, including its working group on arbitrary detention.
The West African bloc ECOWAS -- in calls backed by Western allies -- has threatened to use force as a last resort to reinstate Bazoum, and has been holding separate mediation talks with Niger's leaders.
France keeps about 1,500 soldiers in its former West African colony as part of an anti-jihadist deployment in the Sahel, and coup leaders have demanded a "negotiated framework" for their withdrawal.
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