A suicide bomber has killed 16 people in a Shiite-majority town north of Baghdad a day after an al-Qaida offshoot claimed responsibility for the attacks that killed more than 70 people.

The blast hit a café in the town of Balad, 60 miles north of Baghdad. More than 35 people were wounded, said reports.

Islamic militants have carried out a number of attacks in cafes during the Muslim holy month of Ramadan, which ended last week. In one of the deadliest incidents, 70 people were killed on Saturday in cafes and busy marketplaces.

Al-Qaida affiliate, the Islamic State of Iraq and the Levant claimed responsibility.

"The Islamic State mobilised in Baghdad and the southern states and others to convey a quick message of deterrence on the third day of Eid al-Fitr," the group said, referring to the holiday marking the end of Ramadan.

"They (Shiites) will not dream of security during night or day, during Eid or other [days]," it added.

Assaults on prisons near Baghdad have freed hundreds of prisoners, including leading radical al-Qaida militants. Analysts warned that jailbreaks could lead to an upsurge in sectarian violence.

More than 3,000 people have been killed in the bloodshed that has rocked Iraq since April. Violence is driven by anger among the Sunni Arab minority against the Shiite-led government.