An army official says suspected members of a radical Islamist sect have attacked a besieged city in Nigeria's northeast.

Military spokesman Lt. Col. Hassan Mohammed said suspected Boko Haram members detonated a bomb Wednesday at a roadside shop in the city of Maiduguri.

He said no one was hurt.

However, a hospital worker, who asked for anonymity because he is not allowed to speak to journalists, said a badly wounded soldier was admitted into intensive care.

The attack comes a day after an immigration official, who asked not to be named because senior officials have denied the killing, said suspected sect members killed a colleague.

Boko Haram is held responsible for more than 300 deaths this year alone, according to an Associated Press count.