KANO - Nigerian police have arrested 14 suspected members of an Islamist sect and seized explosives after a gun battle on Saturday left four militants and three policemen dead in the northern city of Kano, the police commissioner said.

Militant group Boko Haram is waging a low level insurgency, which used to be largely confined to Nigeria's remote northeast Borno state, but this year has increasingly plagued other parts of the north and the capital, Abuja.

"One of the suspects, Mohammed Aliyu, noticed that his house was being monitored and mobilised some members of his syndicate. They drove up in three vehicles and attacked the policemen and shot (three) of them dead," Kano police commissioner Ibrahim Idris told journalists on Sunday.

He added that four police officers were wounded.

"Four of the syndicate members were shot dead by the police special anti-robbery squad that responded to the scene."

At the house of a suspected militant where the shoot-out occurred, police found 50 litres of petrol and five gas canisters, some AK-47s, two pump-action shot guns and 1125 rounds of ammunition.

Another suspect's house was found to contain detonators, wires, home-made bomb casings and large quantities of explosives, including gun powder and ammonium nitrate.

Boko Haram have been blamed for scores of shootings and bombings in the north, including a spate of attacks last week in Kano and their heartland of Maiduguri, capital of Borno state. Nigerian security forces have been unable to contain the growing threat of Islamist militants in the north, who this year struck the capital twice, including a suicide car bomb against the UN headquarters that killed 26 people.

Nigerian authorities raided a bomb making factory in Maiduguri on Saturday.