Twenty-three people were killed Monday when suicide bombers blew themselves up in attacks targeting police in Chad, a country on the frontline of the fight against Boko Haram.

Twenty-three people were killed Monday when suicide bombers blew themselves up in attacks targeting police in Chad, a country on the frontline of the fight against Boko Haram.

Another 101 people were wounded in the simultaneous bombings outside the police headquarters and police academy in the capital N'Djamena, according to a government statement read on national radio.

It said four "terrorists" were also killed but did not give details. Earlier, a police official had said two suicide bombers carried out the attacks.

They were the first such bombings in the capital of the north-central African nation, where security has been beefed up since Chad joined the fight against Boko Haram earlier this year.

There was no immediate claim of responsibility for the attacks, which came as police cadets were attending a training course at the academy.

The government statement said the "situation is under control".

Large numbers of Chad's security forces were seen taking up positions on the streets of the capital after the attacks.

President Idriss Deby was expected to return home during the day from an African Union summit in Johannesburg, an official said.

The former French colony is part of a four-nation coalition also including Nigeria, Cameroon and Niger that was created to tackle the Boko Haram insurgency as the group steps up cross-border attacks.

Boko Haram leader Abubakar Shekau has on several occasions threatened to attack Chad and other countries in the coalition.

Paris condemned Monday's blasts, with a foreign ministry spokesman saying France "stands alongside Chad and its partners in the fight against terrorism".