Nigerian terrorist Islamist group Boko Haram have attacked a popular market in Madiuguri, north-east of the country, killing up to 30 people, according to local reports.
Suspected members of the sect, who last week stormed a federal prison in central Nigeria killing one guard and freeing 18 inmates, threw explosives into the fish vendors' section.
They reportedly accused the fishmongers of leaking secret information to the security forces that lead to the arrest of a prominent sect member last week.
Hassan Mohammed, a spokesman for the governmental Joint Task Force that tackles terrorism, said eight Boko Haram members died in a gun battle with security operatives.
Three traders sustained injuries and were being treated in hospital.
"Our men engaged members of the Boko Haram sect in gun battle and we successfully killed eight of the sect members and recovered weapons as well as detonated some IEDs (improvised explosive devices) and recovered some others," Mohammed told Times Live.
The development came after reports of "deep throat" inside Boko Haram, who alleged that senior figures in the country's establishment were bankrolling the group.
Kabiru Sokoto, a member of the sect, has reportedly identified its financial backers.
"The man is co-operating well with us," an unnamed source inside the security forces told the Lagos-based Daily Champion.
Sokoto is a suspect in the deadly Christmas bombing of a church near the capital Abuja, which killed 43 people and left dozens injured.
Boko Haram had previously attacked a number of other prisons to free members and also managed to help Sokoto escape police custody, although he has since been rearrested.
He allegedly admitted that security forces are getting closer to the inner circle of the Islamist radical sect