Iraqi officials say a string of attacks have killed at least 93 people, as the extent of the violence grows clearer and mourners start to bury their dead.

The attacks began early on Thursday in the north of Iraq and ended with deadly bomb explosions near busy markets, restaurants and ice-cream parlours shortly before midnight.

It was Iraq's deadliest day in more than three weeks. The attacks seemed intended to strike fear into Iraqis and undermine faith in the Shia-led government's security measures ahead of what was supposed to be a Eid al-Fitr holiday weekend.

More than 190 people have been killed in violence across Iraq since the start of August, showing that insurgents led by al-Qaida's Iraqi franchise remain a lethal force eight months after the last US troops left the country.

There was no immediate claim of responsibility. Co-ordinated bombings and related attacks are a favourite tactic of the al-Qaida offshoot, known as the Islamic State of Iraq.

Among the higher casualty numbers disclosed on Friday were 21 people killed when a car bomb detonated shortly before midnight near an ice-cream shop in Baghdad's predominantly Shia Zafaraniya district, according to police and hospital officials.

Another bomb exploded near an ice-cream parlour and vegetable stalls in the capital's Sadr City, another poor Shia district. A black, mangled car sat in the middle of the street. Broken chairs and blood-stained fixtures littered the pavement. That blast killed 14, the authorities said.

Officials are tightening security ahead of Eid al-Fitr, which marks the end of the Muslim holy month of Ramadan. They are hoping to thwart further violence as crowds gather in public places such as parks, shrines and mosques to mark the occasion.

Thursday's attacks were the most deadly in weeks. On 23 July, a string of co-ordinated bombings and shootings left more than 100 dead.