People take part in a protest in Baghdad, Iraq, on Oct. 29, 2019. (Xinhua/Khalil Dawood)

Iraq's protest-hit cities saw one of their bloodiest days yet on Thursday as a government crackdown killed nearly 40 demonstrators following the dramatic torching of an Iranian consulate.

The country's capital and south have been rocked by the worst street unrest since the 2003 US-led invasion that toppled Saddam Hussein.

Thursday's violence brought the total death toll since early October to more than 390, according to an AFP tally. 

Crowds outraged at Tehran's political influence in Iraq had stormed and burned down the mission. The Iraqi Foreign Ministry condemned in a statement the attack by some demonstrators on the Iranian consulate in Najaf.

The ministry said the purpose behind burning the Iranian consulate is "to harm the historical relations between Iraq and Iran, as well as with the rest of the world states whose missions are working in Iraq." It reaffirmed its warning that there are some persons who want to derail the demonstrations by distorting the fair demands of the demonstrators.

The Iraqi ministry affirms that "the diplomatic missions operating in Iraq are highly respected."