A suicide bomber struck Baghdad's main vegetable market Sunday, killing at least 18 people in the latest attack claimed by the militant Islamic State (IS) group as Iraqi forces battle the militants for Mosul.

Iraqi forces have pushed IS out of much of the territory it once held, but this bombing and the many others that have preceded it highlight the danger the militants can pose to civilians even as they lose ground.

“A soldier at the gate of Jamila market opened fire on a suicide car bomb after noticing a suspect vehicle but the terrorist blew up his car,” interior ministry spokesman Saad Maan said.

A police colonel and a medical official said at least 12 people were killed and 39 wounded.

Maan said the soldier who opened fire on the attacker was among the wounded.

Another suicide bomber detonated explosives at a market in the Baladiyat area of east Baghdad, killing at least one person and wounding at least seven, officials said.

Jamila is the main wholesale vegetable market in Baghdad and lies in Sadr City, a vast, mostly Shiite neighbourhood in the northeast of the capital which has been repeatedly targeted.

Salam Khalaf, the spokesman for a hospital in Sadr City, said that it received a headless body of a person killed in the Jamila attack who was apparently meant to be a second suicide bomber.

While a hospital employee was searching for the man's identity card, he accidentally detonated a small explosive charge the man was carrying, blowing off a mortuary door but leaving him unharmed, Khalaf said.

The dead man was wearing an explosive belt but it did not go off, he added.

The police colonel also confirmed that the body of a person taken from the scene of the market attack later exploded at the mortuary.

Battle for Mosul

IS issued an online statement claiming the market attack, using a nom de guerre indicating the bomber was Iraqi and saying that he targeted members of Iraq's Shiite Muslim majority, whom the jihadists consider heretics.

IS claimed an attack on January 2 — also in Sadr City — when a suicide bomber blew up a vehicle packed with explosives among a crowd of day labourers waiting for work, killing 35 people.

The militants overran large areas north and west of Baghdad in a swift 2014 offensive that swept through security forces unprepared for the assault.

The number of bombings in the capital declined following the June 2014 offensive, apparently because the militants were occupied with holding territory they seized and later defending against government attacks.

Federal forces and units from Iraq's autonomous Kurdish region have since pushed IS back in a series of battles over a period of more than two years.

On October 17, Iraqi forces launched a massive operation to recapture Mosul, the country's last city in which IS still holds significant ground.

Iraqi forces punched into the city from the east, retook a series of neighbourhoods and are now approaching the Tigris River, which divides the city into its eastern and western sides. The western side, which is the smaller but more densely populated of the two, remains entirely under IS control.

Iraqi forces have also launched an operation to recapture IS-held towns near the Syrian border that along with Mosul and the northern town of Tal Afar are among the last populated areas under the militants control.

Prime Minister Haider al-Abadi said in late December that three months were needed to eliminate IS in the country.

But even if the militants no longer openly hold territory, they can still strike at Iraqi civilians and security forces with bombings and hit-and-run attacks.