Saudi Arabia warned Wednesday of the risks of a civil war in Iraq with unpredictable consequences for the region, after Sunni militants seized large areas from Shia-led government forces.

The unrest in Iraq "carries warning signs of a civil war with unpredictable consequences for the region," Foreign Minister Prince Saud al-Faisal said at the opening of an Islamic bloc meeting in the Red Sea city of Jeddah.

Prince Saud renewed Saudi accusations that "sectarian policies of exclusion" of Iraq's Sunni Arab minority implemented by Prime Minister Nuri al-Maliki's government were responsible for the violence.

This paved the way for countries with "bad intentions" towards Iraq "to go ahead with plots threatening its security, stability, national unity and sense of Arab identity," Prince Saud said.

His remarks came as Iranian President Hassan Rouhani said his country would do whatever it takes to protect Shia holy sites in Iraq against the Sunni militants.

The Iraqi government, which is close to Tehran, has issued a statement accusing Sunni Saudi Arabia of financing the militants.

"We hold (Saudi Arabia) responsible for what these groups are receiving in terms of financial and moral support," the Iraqi government said in a statement, accusing Riyadh of "siding with terrorism".