At least 54 people were killed and 90 wounded in a multiple bomb attack in the northeastern Nigerian city of Maiduguri on Sunday evening, a police spokesman said Monday.

“A suspected Boko Haram suicide bomber detonated IEDs [improvised explosive devices] at a mosque in Ajilari and some insurgents also threw IEDs at a viewing center. Total casualty figure is now 54,” Victor Isuku, a police spokesman in Maiduguri, said.

A Nigerian army spokesman said Sunday that three bombs had gone off.

The blasts hit the country a day after a new audio message purportedly from Boko Haram leader Abubakar Shekau accused the army of lying about successes against the group.

There was no immediate claim of responsibility for the explosions. However, they bore the hallmarks of Boko Haram, which has waged a six-year insurgency to form a state adhering to strict Islamic laws.

The audio recording, said to be of Boko Haram's leader, criticized Nigeria's military for saying it had recaptured villages that had fallen to the group.

Maiduguri is the capital of Borno state, the birthplace of the brutal armed group that has plagued the oil-rich country with violence in recent years.

More than 1,000 people have been killed by Boko Haram violence since President Muhammadu Buhari was inaugurated as president on May 29, vowing to crush Boko Haram.

At the start of 2015 Boko Haram controlled vast swathes of territory across three states in the northeast.

Nigeria's army, aided by troops from Chad, Niger and Cameroon, said it pushed Boko Haram out of most of that land earlier this year. Since then, the group has carried out a number of attacks on public areas.

When asked about the audio recording purportedly of the sect's leader, Usman said experts were trying to establish whether it is Shekau's voice.

Nigeria's military has repeatedly claimed that Shekau has been killed over the last few years only for him to resurface in new videos and recordings, although security sources have said he may have been replaced by impostors.

Al Jazeera and wire services