At least 21 people have been killed and 40 people wounded in a double bombing at a busy market in the centre of the Iraqi capital, Baghdad, officials say.

The explosions happened near shops selling spare parts for cars in the al-Sinak market, according to police quoted by Reuters news agency.

No group has claimed responsibility for the attack.

The Iraqi capital has been experiencing frequent militant attacks that mainly target crowded and public areas.

One bomb was triggered by a suicide attacker while the other was a planted explosive, officials said.

There had been reports that both bombs were improvised explosive devices.