Baghdad (Alliance News) - Sunni militants already in control of large chunks of Iraq have started exporting crude from an oilfield in the north, a local official said Friday as the army reported a new attempt by rebels to capture a major oil refinery.

The jihadist Islamic State in Iraq and the Levant (ISIL) began loading 100 tanks with crude late Thursday from the Ujil field, in the northern province of Salah al-Din, local police chief Shalal Abdul said.

"They sell the crude for 12,000 to 14,000 dollars per tank and use the revenues in financing the organization's (military) operations."

ISIL - an al-Qaeda splinter group - seized the field, one of Iraq's largest, in a swift advance into the country's Sunni heartland in the north and the west last month.

The field, which produces about 20,000 barrels per day, is located outside oil-rich Kirkuk, one of several areas at the centre of a dispute between Baghdad and the autonomous region of Kurdistan.

ISIL exports the crude via Kurdistan to privately owned refineries, Abdul said.

Kurdistan's president, Massoud Barzani, vowed Thursday that Kurdish troops - the Peshmerga - will not withdraw from the disputed areas, including Kirkuk, which they took over following the surge by Sunni-led insurgents into Iraq.

On Friday, the government said it had repulsed a new offensive by ISIL to seize the country's largest oil refinery in Biji, some 200 kilometres north of the capital Baghdad.

"The anti-terrorism troops in collaboration with the Army Ninth Brigade and the air force foiled an attack by ISIL insurgents on the refinery," the spokesman for the Anti-Terrorism Agency, Sabah al-Nouaman, told independent site Alsumaria News.

Since their blitz in Iraq in early June, the ISIL-led rebels have launched several attacks to take control of the Biji facility.

Earlier this week, ISIL leader Abu Bakr al-Baghdadi declared an Islamist caliphate in the territory under the group's control in Iraq and Syria, raising international fears of the emergence of a regional militant enclave.

Al-Baghdadi, the first caliphate of the self-styled caliphate, was reportedly wounded in an overnight airstrike in western Iraq.

"There is news that has yet to be confirmed that al-Baghdadi was injured in the air bombardment carried out by Iraqi troops in the town of Qaem near the Syrian border," Alsumaria News reported, quoting an unnamed Iraqi security official.

The rebels' territorial expansion in Iraq comes as its political factions are at loggerheads over choosing candidates for the country's top three leadership positions - parliament speaker, prime minister and president.

According to rules set up after the US-led invasion in 2003, Iraq's leadership must incorporate all three of the country's major ethnic groups. The speaker has to be a Sunni Muslim, the prime minister a Shiite and the president Kurdish.

Prime Minister Nuri al-Maliki, who has been in office since 2006, faces stiff opposition as he bids for a third term.

His critics accuse him of monopolizing power and marginalizing the Sunni minority.

In a step designed to pressure al-Maliki into backing down, Osama al-Nujaifi, a Sunni leader who headed the former parliament, announced dropping his bid to become speaker of the new legislature, Iraqi media reported Friday.

However, al-Maliki's State of Law bloc dismissed al-Nujaifi's move as an act.

"Al-Nujaifi knows he is rejected by both Shiites and Sunnis. In acting this way, he seeks to save his face," Hanan al-Fetlawi, a lawmaker allied with al-Maliki, said.

Iraq has suffered increasing violence during the last year, much of it blamed on ISIL and aimed at security forces and Shiite civilians.

The Shiite-led government's response, with security sweeps and mass arrests, has further alienated Iraq's Sunnis, from which ISIL and other rebel groups draw their support.

Copyright dpa