The woman – who was identified as Samira Ahmed Jassim or by her nickname "Umm al-Mumineen", which means the mother of believers – was shown confessing in a video played for reporters at a press conference in Baghdad.
The use of female suicide bombers is part of a shift in insurgent tactics to avoid detection at US-Iraqi military checkpoints that have become ubiquitous in Iraq as part of increased security measures.
Iraqi women often are allowed to pass through male-guarded checkpoints without being searched, and they traditionally wear flowing black robes that make it easier to hide explosives belts.
The spokesman would not say where Jassim was arrested because the investigation was ongoing.
But he said the recruits had been from Baghdad and Diyala province.
He also said she had contact with a pair of recently detained insurgent brothers.
In the video, Jassim said she had to talk to one elderly woman several times before persuading her to blow herself up at a bus station.At least 36 female suicide bombers attempted or successfully carried out 32 suicide attacks last year, compared with eight in 2007, according to American military figures.The military said it couldn't provide information on the number of female suicide bombers so far this year, but on Jan 4, a woman who blew herself up in the midst of Iranian pilgrims in Baghdad killed more than three dozen people.Wahida Mohamed Al-Jumaily, a 39-year-old grandmother has lost loved ones in her battle with the terror group - her second husband was killed earlier this year, and jihadists have also killed her father and three brothers.It was deemed she had brought shame on her family by falling love with the soldier, known only as Paul, as she chatted to him a few times while working as a volunteer with refugees.That girl humiliated me in front of my family and friends.