Chadian Prime Minister Saleh Kebzabo on Thursday updated the death toll from nationwide clashes between protesters and security forces to "around 50" and announced an overnight curfew.
The deaths mainly occurred in the capital N'Djamena and the cities of Moundou and Koumra, Kebzabo told a news conference.
He added that the night-time curfew would remain in place until the "total restoration of order" in the hot spots of unrest.
Violence broke out after demonstrators barricaded roads and torched the prime minister's party headquarters as hundreds took to the streets to demand a quicker transition to democratic rule after President Mahamat Idriss Deby seized power last year.
A national unity government was formed on Friday to lead Chad for the next two years until elections. But critics are demanding a swifter return to democracy.
Police fired tear gas and rubber bullets to break up gatherings throughout the city.
The government said security forces acted only in self-defense.
"What happened today is an armed popular uprising to seize power by force and those responsible for this violence will face justice," said Kebzabo.
"The demonstrators had firearms and they are considered rebels."
Kebzabo, a historic opponent of Deby's regime, was named prime minister last week.
"A banned demonstration became an insurrection," spokesperson Aziz Mahamat Saleh told Agence France-Presse (AFP) earlier in the day, saying demonstrators in N'Djamena had attacked "public buildings."
Palls of black smoke could be seen in some parts of the city and the crack of teargas grenades could be heard.
Barricades were set up in several districts and tires were set alight in the main avenues to block traffic.
In an opposition stronghold, streets were deserted and littered with tree branches and piles of bricks. Schools and university establishments were closed.
The headquarters of Kebzabo's UNDR party was also attacked by demonstrators "and partially burned down," UNDR Vice President Celestin Topona told AFP.
France, Chad's former colonial power, condemned the violence, which "notably (featured) the use of lethal weapons against demonstrators."
