She added: “Our Oriental society is not like your Western society. It seems in many of these cases the women have had their husband killed or sent to prison and she feels she has no choice, she is very depressed.”

Female suicide bombers are not a new phenomenon in Iraq or elsewhere, but they have been relatively rare. Since 2003, 43 women have carried out suicide bombings in Iraq, a tiny percentage of the total, according to the United States military. Though the first two cases came in the first year of the war, suicide attacks by women did not really become a trend until 2007, when there were eight such bombings in Iraq. All but one of the female bombers have been Iraqis and most are young, between the ages of 15 and 35, according to the police and American military analysts. Almost all the attacks have been attributed to Al Qaeda in Mesopotamia, which is also known as Al Qaeda in Iraq.

Diyala has been a stronghold for the group since it was chased from Anbar Province in the west in 2004. The province’s attraction was clear: it offers easy hiding places in its palm groves and orchards, and a Sunni-majority population that includes many people who supported Saddam Hussein and are sympathetic to the insurgency.

But in the past year, American and Iraqi forces have had much greater success in killing and detaining the group’s members in the province, as well as thwarting many of its bigger attack plots. The rise in female suicide bombings has directly coincided with the timing, and the locations, of Al Qaeda in Mesopotamia’s biggest loss of manpower in Diyala, Baghdad and Anbar.

“Al Qaeda is always innovating: finding new ways to work,” said Ghanem al-Khoreishi, the police chief of Diyala. “When we destroyed them in fighting, they started to use new methods. And because they knew that women are treated more gently than men, they began to use them.

“The people don’t search them so well even at checkpoints.”

Interviews with police officers and politicians, American military analysts and Iraqi women yield different views of the phenomenon. But many agree that the province’s traditional, conservative and still largely rural society is a factor.