Explosions attributed to several suicide bombings killed at least 23 people and injured more than 100 in Maiduguri, the capital of Borno State in northeastern Nigeria, police announced Tuesday.

"Based on initial investigations, suicide bombers are suspected," said police spokesman Nahum Kenneth Daso in a statement, adding, "unfortunately, a total of 23 people lost their lives and 108 others were injured to varying degrees."

The explosions took place on Monday evening, less than 24 hours after an attack on a military post on Sunday at midnight in a suburb of Maiduguri located a few kilometers from the city's airport.

An AFP journalist present at a hospital in Maiduguri on Monday evening saw dozens of injured people seeking treatment after Monday's explosions, as well as multiple bodies covered with sheets on the sidewalk outside.

"The situation has returned to normal in the affected areas" and security forces have reinforced their "presence and surveillance in Maiduguri and its surroundings," police said in a statement early Tuesday morning.

In December, an unclaimed bomb attack killed at least seven people in a mosque in Maiduguri.

These attacks come after a period of relative calm in the city since the insurgency had been pushed back to remote rural areas.

Maiduguri, the scene of shootings and bomb attacks, with a peak in attacks in the mid-2010s, had been relatively calm for the past few years.

However, violence has persisted in the surrounding countryside and in recent months jihadist groups have intensified their pressure.

Last week, the army confirmed "coordinated attacks" against several military bases in the Northeast, which killed at least 14 people, including 10 soldiers.

The United States recently announced the deployment of 200 troops to Nigeria to assist the Nigerian army in fighting jihadists.

Since 2009, jihadist attacks in northeastern Nigeria, perpetrated mainly by Boko Haram and the rival jihadist group Islamic State in West Africa (ISWAP), have killed more than 40,000 people and displaced around two million, according to the UN.