Chad has arrested at least five suspects and banned religious burqas after suicide bombings blamed on the Islamist Boko Haram killed 34 people, it said Wednesday.
The two simultaneous attacks on Monday were the first of their kind in Chad and appeared to be retaliation by Boko Haram for Chad's leading role in an offensive against the militants.
More than 100 people were injured in the attacks on a central police station and a police school in the capital.
Abderahim Bireme Hamid, minister for the interior and public security, said that, with the arrests, "there has been progress."
Chad is a key Western ally in the fight against armed Islamist groups both in the Sahara and Lake Chad area. Officials of the predominantly Muslim country also said head-to-toe burqas and religious turbans would be banned.
"Even the burqas for sale in the markets will be withdrawn," said Prime Minister Kalzeube Pahimi Deubet, who met religious leaders on Wednesday to discuss the measures.
Oil revenues have helped Chad become a military heavyweight. Its troops were vital in driving Boko Haram militants from territory in northern Nigeria this year.
Its capital serves as a command center for a regional anti-Boko Haram task force made up of troops from Nigeria, Chad, Niger, Cameroon and Benin as well as for France's 3,000-strong Barkhane mission fighting militancy in the region.
Neighboring Niger said on Wednesday its security forces arrested a dozen suspected members of a Boko Haram cell that killed a civilian and kidnapped two youths during an attack on a village in the southeastern region of Diffa this week.