A suicide car bombing on Tuesday killed a parliament member and 24 others in a Shi'ite neighborhood in Baghdad, according to police and medical officials, as Islamic State attacked towns in western Anbar province.
The third straight day of bombings in Shi'ite parts of Baghdad and an offensive in Anbar province that saw strategic towns threatened by Islamic State pointed to the dire security situation in Iraq.
The blast in Baghdad, claimed by Islamic State, occurred in the late afternoon as cars lined up to enter the affluent neighbourhood, home to one of the holiest shrines in Shi'ite Islam, Imam Kadhim.
Police and medics said Ahmed al-Khafaji, a member of the Shi'ite Badr political party and a former deputy interior minister, counted among the dead.
Five police officers were also killed, police and medical officials said.
In a second attack, a roadside bomb killed three passersby on a busy street in the communally mixed district of al-Qahira in northern Baghdad, police and medical officials said.
The attack in Kadhimiya marked the third straight day of bombings there and other mostly Shi'ite neighbourhoods in the Iraqi capital and its outskirts. The blasts have killed at least 77 people since Sunday.
Islamic State, ultra-radical Sunni Muslim insurgents who have seized wide areas of northern and western Iraq, described the bombing as targeting Khafaji, according
to the Site monitoring group.
Islamic State seeks to establish an Islamic caliphate spanning the borders of Iraq and Syria, where it has taken about a third of the country in the course of its civil war.
In western Anbar province, Islamic State has taken two towns this month in the mid-Euphrates river valley, Hit and Kubaisa, as it continues to push eastward in hopes of taking the Haditha Dam, where pro-government Sunnis are fighting jihadists in collaboration with the government.
If the dam falls, Islamic State will control much of the Euphrates water supply and will effectively rule from the Syrian border within range of Anbar's capital Ramadi.
In the Anbar town of Baghdadi 35 miles (56 km) southeast of Haditha Dam, Mayor Naji Arrak warned by telephone: "Baghdadi town has been surrounded by the Islamic State fighters since four days and despite appeals to military commanders in Anbar to intervene, we heard nothing."
In Amiriya Falluja, southwest of Baghdad, the area was surrounded by Islamic State late Tuesday, according to people from the town, who were frantically seeking to call in US air strikes.
One man said the town was surrounded from three sides by tanks and armored vehicles. If Amiriya Falluja fell, it would create a wide opening for Islamic State to mass for a push into Baghdad, nearly 40 km away.
The Iraqi army has been badly damaged since the fall of Mosul, the north's biggest city, in June when at least four army divisions faded away.
Anbar military units have been hurting since last January when soldiers first battled Islamic State and tribes angry at the Baghdad government in the province's capital Ramadi and outside its sister city Falluja.