Islamic State says it has seized Iraqi city of Ramadi

Iraqi government forces have staged a desperate retreat from their last bases in Ramadi, effectively giving the Islamic State group full control of the capital of Iraq's largest province.

An estimated 500 civilians and security forces have been killed since ISIL launched a fresh offensive in Ramadi late Thursday, an official said, warning that those left behind risked being massacred.

"Anbar operations command has been cleared," Muhannad Haimour, spokesman and adviser to the provincial governor, told AFP.

Several security officials confirmed the retreat.

ISIL fighters who already controlled most of the Anbar provincial capital used a wave of suicide car bombings late Thursday and Friday to take most of the city.

Army, police, counter-terrorism and local tribal forces had been confined to the operations command base on the northern bank of the Euphrates and the large judicial compound facing it.

"Ramadi has not fallen -- there are still people fighting in some neighbourhoods," Mr Haimour insisted.

The capture of Ramadi by ISIL marks one of the worst setbacks for the government since it launched nationwide operations to reclaim territory lost to the jihadists in June 2014.

Police Colonel Jabbar al-Assafi said government forces had withdrawn from Ramadi city and redeployed to its outskirts.

"The security forces -- army and police -- have pulled out of Ramadi. They headed to the main highway" west of the city, he told AFP by telephone.

An army lieutenant colonel who was among the troops that withdrew from the operations command centre confirmed that ISIL now controlled all of the main security bases in the city.

"Army and police and all forces that were stationed at the Anbar operations command have pulled out, as they have from the nearby police station and judicial compound," he said, speaking on condition of anonymity.

"Daesh has just taken full control of all main security bases... They torched the main petrol station at operations command as soon as they took over," he said, using an Arabic acronym for ISIL.

The jihadists' major push to take Ramadi two days earlier trapped hundreds of members of Iraqi forces in their bases with no supply lines and insufficient support to fight back.

A video surfaced on Facebook yesterday of soldiers inside a base pleading with their superiors for reinforcements and supplies.

The fighting sparked a fresh wave of displacement, with the International Organization for Migration (IOM) saying 8,000 people had been forced to flee and that numbers were still increasing.

However, some civilians were believed to have been prevented from leaving their homes by ISIL.

"We are extremely concerned about massacres that could be committed in the next hours," Haimour said.

Prime Minister Haider al-Abadi had vowed to send back-up and not abandon the city about 100km west of Baghdad.