Four people were killed and 18 others injured in two separate bomb explosions in Baghdad on Wednesday, a well-informed police source said.

An explosive-charge planted in a minibus carrying passengers went off while travelling in the al-Qahira neighborhood in northeastern Baghdad, killing two passengers and wounding 11 others, the source told Xinhua on condition of anonymity.

The site of the explosion was close to the place of one of Tuesday's deadly bombings where a booby-trapped minibus went off at the intersection of the Nidaa mosque, the source said.

Meanwhile, two more people were killed and seven others wounded in another explosion when a roadside bomb detonated in Adhamiyah neighborhood in northern Baghdad, the source added.

The attacks came a day after five coordinated deadly attacks and a suicide car bombing hit Baghdad, killing up to 127 people and wounding more than 448.

Despite the drop in violence in the past two years, recent series of attacks have raised concerns about the ability of Iraqi security forces to contain violence ahead of the country's national elections next year.