Four car bombs have struck two outdoor markets in predominantly Shiite areas of Iraq, killing at least 31 people and wounding dozens.
The bombings in Baghdad and a town south of the capital were the latest attacks by suspected Sunni insurgents trying to re-ignite sectarian violence and undermine the Shiite-led government.
A recent spike of insurgent attacks comes at a time of anti-government protests by Iraq's disaffected Sunnis, including tens of thousands who held rallies on Friday in western and northern areas.
Demonstrators blocked Iraq's main highway to Jordan near the city of Ramadi, which is the capital of Anbar province and a former al-Qaida stronghold.
Protesters have rejected calls by an al-Qaida-linked group that they take up arms against the government, but there is concern militants are trying to exploit mounting Sunni discontent.
Friday's bombings targeted an outdoor pet market in Baghdad's northern Kazimyah neighbourhood and a vegetable market in the Shiite town of Shomali in Hillah province, south of the Iraqi capital.
Every Friday, Iraqis converge on markets to shop and spend family time during the Muslim weekend. Markets are a frequent target for militants who seek to inflict large numbers of casualties.
In Baghdad, the first car bomb exploded around mid-morning at the entrance to the Kazimyah market, two police officers said.
When panicked shoppers tried to flee the area, a second parked car exploded a few metres away, according to the officers. At least 17 people were killed and 45 were wounded in the two blasts, police said. All the victims were civilians.
About an hour later, two car bombs exploded simultaneously at the Shomali market, killing at least 14 people and wounding 26, two police officers said.