NIGERIAN soldiers have shot dead a suspected media spokesman for Islamist militant group Boko Haram and another high-ranking member, a military official and a security source say.

Troops involved in the operation on the outskirts of the city of Kano on Monday said one of those killed was suspected to have been the Boko Haram spokesman who has used the alias, Abul Qaqa.

A second man, believed to be the "field commander" for Kogi and Kaduna states as well as the capital, Abuja, was also shot and later died from his wounds, according to a high-ranking security source.

Authorities also located a cache of explosives at a house in the city, the source said.

"We carried out an operation early this morning in which we killed a media man of Boko Haram terrorists and arrested two field commanders of the sect," said Lieutenant Iweha Ikedichi, spokesman for a military task force, adding that he did not have their exact identities.

He said a large quantity of explosives were found in the house and a bomb squad had deployed to clear it.

The operation that led to the shootout occurred at a checkpoint and was carried out with the use of intelligence information, soldiers said.

According to a soldier, the three suspects were coming into Kano early on Monday along with a woman they were transporting to receive medical treatment.

The alleged spokesman was said to have resisted and was killed in the shootout. The woman who was with them allegedly told security forces he was the person who uses the alias Abul Qaqa.

Statements are often issued on behalf of Boko Haram in the name of Abul Qaqa, and someone identifying himself with that name has regularly held phone conferences with journalists.

Earlier this year, security sources said a suspect believed to be a person who goes by the alias, Abul Qaqa, had been arrested.

At the time, a purported Boko Haram member confirmed one of the group's high-ranking members had been arrested, but refuted reports that the detained person was its spokesman.

Boko Haram has been blamed for more than 1400 deaths as part of its insurgency in Nigeria's northern and central regions.

Its attacks have grown increasingly deadly and sophisticated, including suicide bombings at UN headquarters in Abuja and an office for one of the country's most prominent newspapers.

Nigeria, Africa's most populous nation and largest oil producer, is divided between a mainly Muslim north and predominately Christian south.