The junta-ruled African country is currently in the process of a so-called national dialogue, with the aim to hold "free and democratic elections" within 18 months, according to the military council's head General Mahamat Idriss Deby Itno in late August.

But the process has been repeatedly delayed -- with major armed rebel groups and opposition parties boycotting it as they say it is a narrow dialogue between the government and those friendly to it.

Police and the army since Thursday surrounded the headquarters of the opposition Transformers party -- which doubles as the home of party leader Success Masra -- in Chad's capital of N'Djamena.

Authorities also arrested at least 84 of its activists for "unauthorised demonstration" and "disturbing public order", police said.

The Transformers party said the number is closer to about 280 detained.

But on late Sunday, Chadian minister of public security Idriss Dokoni Adiker said "all those arrested have been released this evening".

"(They) will return to their homes tomorrow morning for security reasons," he told AFP.

He added that Success Masra's home had also been freed.

The lifting of the siege and the promised return of the arrested activists were confirmed to AFP by Masra Ndolombaye, vice president of the party.

The Transformers party is a member of a coalition -- Wakit Tamma -- comprising opposition movements and civil society organisations, all of whom refuse to take part in the ongoing dialogue.

The dialogue has also been shunned by two of the country's main armed rebel movements.

Junta leader Deby Itno, 38, seized power in April 2021, after the death of his father -- strongman President Idriss Deby Itno -- who was killed on the battlefield as the army was locked in conflict with rebels opposed to his 30 years in power.

The younger Deby Itno now leads a military council of 15 generals. After dismissing the government, dissolving parliament and abrogating the constitution, he promised Chadians and the international community to return power to the civilians after a national reconciliation dialogue.

Launched late last month, the process was suspended on Saturday until Monday -- 15 days before its planned ending.

The forum, which currently includes some 1,400 delegates, is unlikely to result in genuine national reconciliation given the boycott.

Two of the country's three most powerful armed rebel movements have refused to sign a peace agreement previously reached between the junta and some 40 of the 50 armed groups.

Since its independence from France in 1960, Chad's history has been paved with coups and attempted coups and rebel offensives.