Iraqi troops battled to dislodge an al-Qaeda splinter group from the city of Tikrit yesterday after its leader was declared caliph of a new Islamic state in lands seized this month across a swathe of Iraq and Syria.

Alarming regional and world powers, the Islamic State in Iraq and the Levant (Isil) claimed universal authority, declaring its leader Abu Bakr al-Baghdadi was now caliph of the Muslim world – a mediaeval title last widely recognised in the Ottoman sultan deposed 90 years ago after World War I.

“He is the imam and caliph for Muslims everywhere,” group spokesman Abu Muhammad al-Adnani said in an online statement on Sunday, using titles that carry religious and civil power.

The move, at the start of the holy month of Ramadan, follows a three-week drive for territory by Isil militants and allies among Iraqi’s Sunni Muslim minority.

The caliphate aims to erase colonial-era borders and defy the US- and Iranian-backed government of Shi’ite Prime Minister Nuri al-Maliki in Baghdad.

It also poses a direct challenge to the global leadership of al-Qaeda, which disowned Isil, and to conservative Gulf Arab Sunni rulers, who already view the group as a security threat.

The Iraqi government has appealed for international help and has accused Sunni neighbours, notably Saudi Arabia, of having fostered Islamist militancy in Syria and Iraq.

Iraqi army spokesman Qassim Atta said declaring a caliphate could backfire by showing that Baghdadi’s group posed a risk to other nations: “This declaration is a message by Islamic State not only to Iraq or Syria but to the region and the world.

Isil claimed universal authority, declaring its leader caliph of the Muslim world

“The message is that Islamic State has become a threat to all countries,” he said.

“I believe all countries, once they read the declaration, will change their attitudes because it orders everybody to be loyal to it.”

The fighting in Iraq, the second biggest oil producer in Opec, has contributed to a rise in analysts’ forecasts for the global price of crude, a Reuters poll found. The consensus view of the average 2014 price of a barrel of Brent rose more than $2 to $108 in the course of the past month.

Fighters from the group overran the Iraqi city of Mosul on June 10 and have advanced toward Baghdad, prompting the despatch of US military advisers.

In Syria, Isil has captured territory in the north and east, along the desert frontier with Iraq.

Maliki’s government, with the help of Shi’ite sectarian militias, has managed to stop the militants short of the capital but has been unable to take back cities its forces abandoned.

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