BEIRUT (Reuters) - Iranian President Mahmoud Ahmadinejad urged regional countries on Monday to work for unity in Iraq, which has seen weeks of protests against Shi'ite Prime Minister Nuri al-Maliki, warning that any disturbance there would affect the whole Middle East.

"If a fire breaks out it will burn everyone," Ahmadinejad, speaking through a translator, said in an interview with Al Mayadeen television. "I said with all honesty, those who are interfering will be subject to harm".

A suicide bomber attacked a government-backed militia in Iraq on Monday, killing at least 22 people. It was the seventh suicide bombing in a month in Iraq.

(Reporting by Mariam Karouny; Editing by Pravin Char)