Iraqi security officials say another 30 people were wounded in the blast that hit Imam Mahdi al Muntadhar Mosque in Baladiyat neighbourhood, near the densely-populated district of Sadr City.
A suicide bomb blast at a Shia mosque in eastern Baghdad killed at least 10 people and wounded 30 others on Friday, Iraqi security officers said.
The explosion hit Imam Mahdi al Muntadhar Mosque in Baladiyat, near the massive and densely populated district of Sadr City.
"At least one attacker wearing a belt of explosives tried to enter the building but was stopped by the guards, and detonated himself outside," said one officer.
There are conflicting reports on the death toll, as some sources say seven people were killed in the attack.
Security forces were quickly deployed to cordon off the site.
There was no immediate claim of responsibility.
Conflict and sectarian war
Iraq has witnessed a rare period of relative calm in recent months after decades of back-to-back conflict, including years of sectarian violence that regularly saw dozens killed in explosions in Baghdad.
In 2017, Iraq declared victory against the Daesh terrorist group, which had also carried out mass attacks against civilians in the capital.
The improved security situation has led officials to dismantle the concrete blast walls, barbed wire, and checkpoints that had become ubiquitous in Baghdad.
But occasional hit-and-run attacks have continued.
Last month, at least eight people were killed and 15 wounded in a suicide bombing at a market in eastern Baghdad.
In November, explosions in several Shia-majority districts killed six people, most of them civilians.