Two separate car bombings in Baghdad on January 5 killed more than a dozen people and wounded numerous others, with the Islamic State (IS) extremist group claiming responsibility for one of the attacks.

Iraqi officials said a vehicle exploded in a predominately Shi'ite neighborhood in the Iraqi capital, killing at least six people and wounded 15 others.

Police said the explosives-laden car was parked near a market in Baghdad's eastern neighborhood of Al-Obaidi when it detonated.

IS claimed responsibility for the attack, saying it targeted a gathering of Shi'a, considered apostates by the Sunni militants.

The second blast hit a security checkpoint in central Baghdad's Bab al-Moadham district, killing eight people.

There was no immediate claim of responsibility for the second car bombing.

Attacks across Baghdad over the past week, some claimed by the IS group, have killed dozens of people.

The attacks came as Iraqi security forces, backed by U.S. air strikes and militia fighters, battle to retake the northern city of Mosul from IS fighters.

Iraqi military officials said the country's forces on January 5 had launched an offensive against IS militants near the Syrian border in a bid to recapture towns in the area.

"A military operation has begun in the western areas of Anbar [Province] to liberate them from" IS forces, AFP quoted Lieutenant General Qassem Mohammedi, head of Jazeera Operations Command, as saying.

With reporting by Reuters, AP, AFP, and dpa