The Islamic State of Iraq and the Levant (ISIL) group has taken over the main government compound in the western Iraqi city of Ramadi, and edged closer to what would be their biggest victory in Iraq this year, officials have said.

Hikmat Suleiman, the spokesman for Anbar's governor, told Al Jazeera that the fighters managed to seize the heavily fortified complex on Friday mainly due to a lack of backing from the central Baghdad government.

"For months we were complaining and telling the Security Ministries that there was no coordination," he said, adding that the military ignored requests for much needed weapons.

The government compound contained Anbar's governor's office, police headquarters and intelligence headquarters.

ISIL itself issued a statement in which it said its fighters "broke into the Safavid government complex in the centre of Ramadi".

The operation "resulted in the control of it after killing the 'murtadeen' then blowing up the adjacent buildings of Anbar's governorate and the Safavid Anbar police HQ."

Safavid is a term used by ISIL in a derogatory way to refer to government forces and "murtadeen" designates Sunni tribal fighters battling alongside the government.

But Suleiman denied that the city of Ramadi had fully fallen to ISIL, as the Anbar Operations Command, which is the military command in Ramadi, remains under the control of authorities.

Al Jazeera's Osama Mohamed, reporting from Iraq's capital Baghdad, said that Iraqi army helicopters have continued to strike several parts of the government compound in an attempt to regain control over it from ISIL.

Provincial council member Adhal Obeid al-Fahdawi had described the situation as "critical" moments earlier and said civilians were fleeing the city centre, the second time in a month they have done so following another ISIL offensive in April.

"Families are trying to flee on foot, leaving their cars and homes behind, but most areas around Ramadi are under ISIL control," said Sheikh Jabbar Adjadj al-Assafi, a tribal leader.

The loss of the capital of Anbar province, which Prime Minister Haider al-Abadi had said would be the next target of government forces after wresting back Tikrit last month, would be a major setback for Baghdad.

ISIL has threatened to take control of Ramadi for months and the breakthrough came after a wide offensive on several fronts in the province, including an assault using several suicide car bombs in Ramadi on Thursday.