N'Djamena - Eleven people died early Monday when Chadian police launched a raid against suspected Boko Haram jihadist militants in a district of the capital N'Djamena, police said.
"Five officers, five Boko Haram elements and one police informant" died in the operation in which officers seized several suicide belts, national police spokesman Paul Manga told AFP.
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The assault follows a June 15 double suicide bombing blamed on the armed Islamist movement from neighbouring Nigeria, which killed at least 33 people in N'Djamena in the deadliest attack of its kind in the city.
On Sunday, Chadian troops stationed in neighbouring Cameroon killed "eight Boko Haram elements" in a raid into Nigeria, a military source said meanwhile.
Before Monday's raid in the capital, Chad's chief prosecutor announced "the dismantling (of a Boko Haram cell) and the arrest of 60 people" as part of an inquiry into the suicide bombings.
"A terrorist cell was identified and taken down. Sixty people were detained," including Nigerians, Chadians, Cameroonians and Malians, prosecutor Alghassim Kassim stated.
Kassim said that one of three people behind the June 15 attacks all killed in action by security forces had been positively identified, while the identity of the two others was being checked.
"The debris left by the kamikaze bombers enabled us to determine that the terrorists were wearing specially-made explosive vests in black fabric," Kassim said.
"Fragments (of the bombs) collected at the scenes of the attacks are identical," he added.
The suicide bombings by three people targeted the police headquarters and the police training school in N'Djamena and also wounded 101 people, according to the latest toll from the prosecutor's office.
A score of people injured in the blasts are still in hospital, one of them in serious condition.
While nobody has taken responsibility for the bombings, N'Djamena has blamed them on Boko Haram, a radical force that launched a bloody uprising in northeast Nigeria in 2009, killing thousands of civilians and putting more than a million to flight.
Boko Haram has several times threatened Chad, whose troops entered Nigeria at the beginning of February this year as part of regional military intervention to battle the Islamic sect.
Jihadist fighters are also active across the borders of Cameroon and Niger, whose frontiers converge in the arid Lake Chad region with those of Chad and Nigeria.
Chadian soldiers based at the border town of Fotokol in the far north of Cameroon on Sunday intercepted Boko Haram fighters seeking supplies in the Nigerian frontier town of Gamboru, an army source said.
"During this operation, the Chadian army killed eight Boko Haram elements and recovered a vehicle stocked with food, six motorbikes and hand grenades," the source said.
Fotokol resident Umar Babakalli told AFP that Cameroonian soldiers also took part in the raid.
"There was violent combat and we could hear sustained gunfire from here. Three hours later, the troops returned to Fotokol and applause from the population," he said, adding that 10 captured Islamists were brought back.
The Chadian air force on Sunday bombed Boko Haram positions on islands in Lake Chad and the raids resumed on Monday morning, the military source said.
In reprisal for the June 15 bombings in N'Djamena, Chadian aircraft struck Boko Haram positions inside Nigeria, destroying six of the insurgents' bases, according to the general staff.
Security has been further stepped up in Chad's capital, with frequent identity checks and searches since the suicide bombings.
The government has also forbidden women from wearing the full-face Islamic veil throughout the country as a security measure.
Many suicide bomb attacks in Nigeria in the past six years have been carried out by kamikaze women who hid their explosives under their clothes.