At least 15 people were killed in an explosion near a Baghdad mosque on Friday, according to reports.
The blast occurred as Shiite worshippers were participating in an Ashura holiday procession to the mosque in the al-Dora neighbourhood of southern Baghdad.
Iraq's borders were closed for five days starting Thursday in an effort to tighten security during Ashura, a major Shiite holiday.
The country's National Security Council recommended the closure.
Attacks during Ashura last year killed more than 180 people in Baghdad and Karbala, south of the capital.