"A suicide bomber blew up his explosive belt while he was surrounded by police near a public garden in Al-Shoala district," a mainly Shiite northern neighbourhood of the capital, the statement by the security forces said.

IS claimed responsibility for the attack and said it killed 15 people, while naming the bomber as Abu Umar al-Ansari.

"He entered into the crowd of apostates and detonated his explosive belt, killing 15... and wounding over 19 others", it said in a statement.

A police source told AFP five people had been killed and 16 others wounded in the overnight bombing, which hit people who had gathered after breaking their daily Ramadan fast.

Those killed were a woman, a girl and three police officers, according to the source.

Municipal workers cleaned human remains, blood stains and glass from the pavement, while damaged police vehicles were also cleared from the scene.

Images circulating on social media showed the vehicles with their bodywork damaged and windows blown out.

One of the dead police officers was named as Lieutenant Rami Dhaher, an intelligence officer, who was hailed as a "hero" in the media.

The dead officer's name was also cited in the IS statement claiming the attack.

The attack came on the seventh day of Ramadan fasting, a period regularly hit by bloody extremist violence in Iraq since the US-led invasion that toppled dictator Saddam Hussein in 2003.

Cafes in Iraq are particularly busy at night during this Islamic holy month, with families and friends gathering to relax and eat before the fast re-starts at dawn.

Iraq in December claimed victory over the Islamic State group after a gruelling campaign to retake swathes of territory captured by the Sunni jihadists, but IS still carries out sporadic bombings.