The alleged bomb factory was near Suleija, a town outside the capital Abuja that has been hit by attacks including a deadly blast at an electoral office on the eve of April's parliamentary vote that killed at least 13.
An explosion near a church in Suleija in July killed at least three people.
A suspect from the neighbouring nation of Niger has been among those arrested in connection with the violence in Suleija and has allegedly confessed, secret police spokeswoman Marilyn Ogar told journalists.
The suspects were linked to the Nigerian Islamist sect Boko Haram, which has been blamed for scores of attacks in the country, said Ogar.
"A non-descript building where the improvised explosive devices are assembled has been uncovered," she said.
Ogar said materials recovered included a gas cylinder, detonator materials and other items.
Authorities did not speak of any connection to the August 26 suicide bombing of UN headquarters in Abuja that killed at least 23 people.
Nigerian authorities have come under intense pressure to put a stop to a wave of bomb blasts in recent months, particularly following the UN attack, one of the deadliest targeting the world body.
Boko Haram has claimed responsibility for the UN attack, and the secret police have claimed it was masterminded by an Al-Qaeda linked suspect who recently returned from Somalia. The suspect has been declared wanted.
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