Hashd al-Shaabi say munitions depot destroyed in blast, which was followed by several explosions in nearby areas
At least 15 people were killed and scores wounded on Friday when blasts, including at a weapons storage facility, rocked northeastern areas of Baghdad, security sources said.
Accounts of the incident differed and it was not immediately clear whether the blasts were accidental or caused by an attack.
The largest explosion sent a ball of fire into the sky at a weapons depot used by Asaib Ahl al-Haq, a powerful member of the Hashd al-Shaabi militias, in the Obeidi area on the outskirts of the city.
"The blast took place in a weapons storage facility on a Hashd al-Shaabi base," Ahmed al-Assadi, the organisation's spokesman, told AFP without elaborating.
The Hashd al-Shaabi is a large paramilitary force which is nominally under the authority of the prime minister but is dominated by powerful Iran-backed Shia militias.
An interior ministry official said the explosions were caused by rockets, but it was not clear whether the rockets had been fired from outside the base or were set off by fire at the weapons storage facility.
Several other blasts were reported in nearby areas of northeastern Baghdad.
A bomb struck a shopping street in Ghazaliya, killing two people and wounding eight, police said.
Attacks on two vegetable markets killed five people and wounded 20, the interior ministry said.
Three were killed in a bomb attack on a commercial area in west Baghdad, police said.
The blasts came as tens of thousands of Shia faithful from across Iraq and abroad converged on the Kadhimiyah shrine in Baghdad to commemorate the death of Mohammed al-Jawad, the ninth Shia imam.
IS attack kills nine soldiers
Fighters from the Islamic State (IS) group also killed nine members of the Iraqi security forces in clashes that broke out in a remote area north of Baghdad, security officials said Friday.
The clashes broke out when IS fighters based in the Hamreen mountain range attacked army and police forces in an area called Mutaibijah, 110km north of Baghdad.
The area lies on the banks of the Udhaim River, near the mountain hideouts where pockets of IS militants remain after Iraqi forces took back control of most regions east of the Tigris in 2015 and 2016.
"We have nine killed and 24 wounded among the security forces," an army lieutenant colonel from the Samarra operations command told AFP.
"The attack started around 10pm last night," he said.
A lieutenant colonel in the federal police said "Daesh (IS) fighters came down the river and down the mountain to attack security checkpoints."
He said the IS fighters eventually pulled back and that the security forces were back in control of the area.
A security official in Dhuluiyah, about 30km south of the site of the attack, said tribal fighters from his town tried to assist the security forces.
"They were stuck on the road because of security restrictions... but when they reached the area, they saw destroyed military vehicles and bodies of security forces completely charred," he said.
IS militants no longer have fixed positions in populated areas in the region, but there is an unknown number of militants holed up in the Hamreen mountains, a range that cuts across the provinces of Diyala and Salaheddin.
Iraqi security forces are battling IS farther north as part of shaping operations for a broad offensive against Mosul, a large northern city that is IS's last major urban stronghold in Iraq.