Fighters from the Islamic State of Iraq and the Levant (ISIL) have launched a string of attacks on an Iraqi army headquarters near Fallujah, killing at least 20 soldiers.

Al Jazeera's Imran Khan, reporting from Baghdad, said ISIL suicide bombers detonated eight fortified car bombs near the army's headquarters on Sunday.

Our correspondent said the group had mounted an attack on missile batteries first and then moved towards the bases.

He said ISIL had been "learning to exploit" the Iraqi military's weaknesses.

"They're using these car bombs to devastating effect. These car bombs are very difficult for the Iraqi security forces to defend against."

Fallujah, in Iraq's Anbar province, is less than 70km west of Baghdad.

Our correspondent said there were also reports that another 33 Iraqi soldiers had been killed in an ambush near Ramadi, also in Anbar, but authorities have yet to confirm the toll.

At least 13 soldiers have been confirmed dead near Ramadi.

Our correspondent said the battle to reclaim Ramadi in Anbar province, which had been taken by ISIL, was "in full flow".

While a government spokesman said that the Iraqi forces were gearing up to retake the province, he said they needed more help from their allies.