BAGHDAD (Reuters) - Al Qaeda leader Ayman al-Zawahri on Thursday called on Iraq’s Sunnis to prepare for a “long guerrilla” war as Islamic State militants lost more land near their de facto capital Mosul.

FILE PHOTO - Al Qaeda's Ayman al-Zawahri speaks from an unknown location, in this still image taken from video uploaded on a social media website June 8, 2011. Social Media Website/File Photo

Islamic State (IS) has lost this year about a half of the territory it conquered in 2014 and 2015 in Iraq in battles against government and Kurdish forces backed by a U.S.-led coalition as well as Shi’ite militias supported by Iran.

The ultra-hardline group is also retreating in neighbouring Syria against an array of U.S.-backed Syrian and Kurdish forces and the government army backed by Iran and Russia.

IS split from al-Qaeda in 2014 and its chief Abu Bakr al-Baghdadi doesn’t recognise the leadership of Zawahri who succeeded Osama bin Laden after his killing in 2011.

Zawahri reprimanded Al-Baghdadi for an extreme interpretation of Islam and the ‘’bloodletting’’ which, he said, gave ``Safavid Iran and its subservient government in Iraq ... a pretext to eradicate the Sunnis.’’

“The Sunnis of Iraq should not just surrender upon the fall of (their) cities into the hand of the Shi’ite Safavid army,’’ Zawahiri said in a video distributed by supporters, using a derogatory term for the army of Iraq’s Shi’ite-led government.

“Rather they should reorganize themselves in a long guerrilla war in order to defeat the new Crusader-Safavid occupation of their areas as they defeated them before.”

He also called on ``the heroes of Islam among the mujahideen of Syria to assist their brothers in Iraq in reorganizing themselves, because they are fighting the same battle.’’

Zawahri did not say what specific group in Syria he was addressing his message to since the Al-Nusra Front cut its links with al-Qaeda last month and took a new name, ‘’Jabhat Fatah al-Sham.’’

Zawahri’s video was aired as Iraq’s Prime Minister Haider al-Abadi announced capturing the oil province of Qayyara, 60 kilometres (38 miles) south of Mosul. [L8N1B639P]

“The liberation of Qayyara is an important step toward achieving the larger goal of restoring Mosul,” Abadi said

Iraqi forces last month captured the Qayyara airbase which it plans to use as a hub to support forces advancing on Mosul.

Abadi hopes to take back Mosul this year, effectively defeating IS in Iraq. it was from Mosul’s Grand Mosque that Baghdadi declared his ‘caliphate’ two years ago.