He noted that in recently two teenage boys blew themselves up in suicide attacks. Children have long been used as lookouts for fighters and incidents of teenagers engaging in attacks have taken place in the past, the military has said.

In another raid in Diyala province, which remains a haven for Al Qaeda in Iraq, US soldiers discovered a script outlining scenes in which children question and execute hostages, plant bombs and fire sniper rifles, Smith said. The second raid was carried out December 8 in the town of Muqdadiyah.

Smith also showed an image of a young boy wearing a vest that the military believed was a suicide belt.

The US military says it has 600 children in custody and that militants were using children more and more as fighters.

Iraqi Defense Ministry spokesman Mohammed Askari said that he suspected militants were abducting more children for ransoms and also to use as foot soldiers. He showed video at the news conference taken of a raid last week in Kirkuk, where Iraqi soldiers rescued a 11-year-old boy who had been kidnapped.

Smith also said that there had been an increase in suicide bombings by women in Iraq. Before 2007 only five women had committed such attacks. Since the beginning of last year there have been at least 10 attacks involving women, four of them this year.