BAGHDAD, July 22 (Xinhua) -- At least 22 people were killed and 45 others wounded in a car bomb explosion in the capital Baghdad on Tuesday, a source from the Interior Ministry said.

A suicide bomber blew up himself at a checkpoint in a Shiite- majority district of Kadhimiyah area, north of Baghdad, killing 22 people and injuring 45 others, the source told Xinhua on condition of anonymity.

Iraq has been witnessing some of the worst violence in years. Earlier on Tuesday, Iraqi security forces killed about 117 insurgents in a series of battles with the Sunni militant groups across Iraq, as the government forces were trying to take back the lands seized by rebel fighters recently.

More than one month ago, armed Sunni insurgents, spearheaded by the Islamic State in Iraq and Levant, launched a surprise offensive on Iraqi security forces. The group has captured a large part of the country's northern and western territories.

Terrorist attacks and violence have killed 5,576 civilians and wounded more than 11,666 others in Iraq in the first half of this year, according to a report released on Friday by the UN Assistance Mission for Iraq and the Office of the High Commissioner for Human Rights.