The government in Chad said Thursday that it had foiled an "attempted destabilisation" plot by army officers and a prominent human rights activist.
A group of 11 officers, led by Baradine Berdei Targuio, president of the Chadian Organisation of Human Rights, were behind the attempt, according to a government statement.
The security services arrested those responsible some time after December 8, the statement added.
A formal investigation had been opened for "violation of the constitutional order, criminal association, illegal possession of a firearm and complicity", said Communications Minister and government spokesman Aziz Mahamat Saleh.
The investigating magistrate leading the case has charged them and ordered their detention, he added.
"The investigation is following its course and the government means to do everything to shed light on this affair and to determine responsibility," Saleh said.
Targuio was sentenced in February 2021 to three years in jail on charges of undermining the constitutional order for having written that Chad's then leader, General Idriss Deby Itno, was seriously ill.
Deby, who died in April 2022, has been replaced by his son, General Mahamat Idriss Deby Itno.
Outlawed demonstrations were held on October 20 to mark the date when the military junta had initially promised to cede power -- a deadline that has now been extended by two years.
Around 50 people died, including 10 members of the security forces, according to an official toll.
But opposition groups say the real count was much higher, and allege that unarmed civilians were massacred.
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