BAGHDAD (AFP, REUTERS) - Bombs left inside busy markets in mainly Sunni Muslim districts of Baghdad killed at least 23 people on Thursday. The deadliest attack took place in Saba'a al-Bour on the capital's northern outskirts, where three bombs exploded killing at least 15 people.

Militants in Iraq often bomb areas where crowds of people gather, and they have targeted markets, football fields, cafes, mosques, weddings and funerals this year.

Iraq is witnessing the worst violence since 2008, when the country was just emerging from a brutal sectarian conflict. There are persistent fears that Iraq will return to the all-out Sunni-Shi'ite sectarian violence that peaked in 2006-2007 and killed tens of thousands of people.

With the latest violence, almost 700 people have already been killed this month and over 4,500 since the beginning of the year.

Diplomats and analysts say the Shi'ite-led government's failure to address the grievances of the Sunni Arab minority, who complain of political exclusion and abuses at the hands of the security forces, has driven the spike in violence this year.

The civil war in neighbouring Syria has also fuelled sectarian tensions in Iraq.