The Islamic State of Iraq and the Levant(ISIL) group has launched a major offensive against the strategic Iraqi city of Haditha with hundreds killed during three days of heavy fighting, a tribal source said on Tuesday. ISIL's offensive against Haditha came less than 10 days after the Iraqi military took over most of Anbar province’s capital of Ramadi - forcing its fighters to withdraw in one of the biggest advances for the army since the armed group took over large swaths of Iraq and Syria in 2014. Naeem Alqoad - a prominent member of Albu Nimr, one of two tribes in Haditha resisting ISIL's assault - told Al Jazeera that dozens of Iraqi security forces and tribal fighters were killed and wounded after attacks on security posts. Alqoad said tribal-led forces have killed at least 250 ISIL fighters. "More than 100 of ISIL's cars have also been destroyed," he added. Reports have also emerged of civilians being taken hostage by the armed group. Alqoad described the foreign coalition's air strikes as "ineffective and weak". ISIL managed to continue the unrelenting offensive because of reinforcements from neighboring Syria and weapons seized from military installations in towns and villages around Haditha, he said. Mabruk Hamid, the mayor of Haditha, called on the Baghdad government to "immediately intervene" and send reinforcements to back the resistance. Hamid said barriers erected by tribal fighters around Haditha had been destroyed by ISIL's attacks, which included dozens of suicide bombings.