BAGHDAD — When hundreds of Al-Qaeda fighters in armored trucks attacked the northern Iraqi town of Shirqat with machine guns last week, the local army unit called for backup and set off in pursuit.



But after a two-hour chase through searing desert heat, most militants vanished into a cluster of Kurdish villages where the Iraqi army cannot enter without a nod from regional authorities.



It was just one example of how distrust between the security forces of Iraq’s central government and of its autonomous Kurdish zone helps the local wing of Al-Qaeda, the once-defeated insurgents who are again rapidly gaining ground, a year and a half after US troops pulled out.



“We had to wait more than two hours to get the required permission to go after them,” an Iraqi military officer who took part in the operation 300 km north of Baghdad said. “While were we waiting, they simply disappeared.”



The Shiite-led Iraqi government and Kurdish authorities are now looking at examples like the Shirqat attack and considering the once unthinkable — launching joint security operations and sharing intelligence — to combat the common enemy of Al-Qaeda.



Such cooperation has been extremely rare since US troops left at the end of 2011, while the central government and the autonomous Iraqi Kurdistan region in the north have been locked in an increasingly hostile dispute over land and oil.



That the two sides are publicly contemplating working together underlines how worried they are about the insurgency and the threat of Iraq slipping back into all-out sectarian war.



The conflict in neighboring Syria and discontent among Iraq’s minority Sunnis has dramatically escalated the threat posed by Al-Qaeda in the past year, leading to violence unseen in Iraq since the height of the US-led war five years ago.



Al-Qaeda fighters, who once held sway over most of Iraq’s Sunni areas until they were beaten by US and Iraqi troops and their local tribal allies during the “surge” campaign of 2006-07, are again on the ascendant.



Last year they merged with a powerful Islamist rebel group in neighboring Syria, forming the Islamic State of Iraq and the Levant. The combined group controls whole swathes of territory on both sides of the frontier and is fighting Kurds and Shiites alike in its goal of setting up a strict Sunni Islamist state across the heart of the Middle East.



In Iraq, Al-Qaeda fighters have been able to carry out ever more frequent and audacious attacks on government targets, culminating with a mass jailbreak last month when they attacked two prisons and sprung hundreds of militants in the biggest insurgent military operation in Iraq in at least five years.



Throughout, the security forces of Iraq’s Shiite-led government have been outmatched, unable to bring security to Baghdad or protect Shiite areas in the south, much less sweep fighters from northern Sunni areas under their grip.



Al-Qaeda’s presence has become strongest in parts of northern Iraq, including areas that have often been disputed between government and Kurdish forces.



Fighters now control most of the villages and towns in an area known as the Hamrin Mountains basin, which links the northern provinces of Diyala, Salahuddin, Kirkuk and Mosul, say security officials, residents and local lawmakers.



As they did before they were beaten back in the George W. Bush-era “surge”, they earn funds by extorting tribute from local businesses, giving them greater authority than the state.



Officials in Baghdad say territorial disputes with Kurdish forces are partly to blame for the inability of the government to exercise control.



“The disputed areas have become havens for Al-Qaeda militants and leaders. Al-Qaeda’s biggest hotbeds are located there,” said a senior Shiite lawmaker and member of the Security and Defense parliamentary committee.



“The security forces have no real control over these areas, mainly because of the conflict between the central government and the Kurdistan Regional Government,” said the lawmaker, requesting anonymity.



The highly-trained and capable Kurdish militia fighters, known as Peshmerga, would be a useful ally for Baghdad after years in which they were rivals. — Reuters