At least six Kurdish troops have been killed in an air strike in north-eastern Iraq, as the Baghdad government stepped up its campaign against Sunni militants.

It was not clear whether the attack deliberately targeted the Kurdish fighters or whether the air force mistook the Kurdish troops for Sunni militants.

The six Kurdish Peshmerga troops were killed close to the town of Jalawla, which has witnessed heavy fighting in recent days between Iraqi security forces and Sunni militants linked with Isis (Islamic State of Iraq and the Levant.)

The secretary general of the Kurdish security forces, Jabber Yawar, told Reuters that only two people had died near Jalawla, describing the attack as a shelling. He said talks with Iraqi authorities were underway to ascertain what exactly happened.

The conflicting accounts reveal the chaotic and fast-changing security situation throughout the country, where disparate groups are vying for power and autonomy from the central government.

While local media reports suggested the air strike was a case of mistaken identity, the murkiness and lack of confirmation leave open the possibility of a deliberate attack.

The Kurds have been in a long-running dispute with the Baghdad over the right to export and market oil independently of the central government. While those in charge in the cities of Irbil and Baghdad view Isis as a threat, the two sides have yet to announce a formal alliance against the Sunni terror group.

Meanwhile, the Kurdish leadership has taken advantage of the Isis advance to seize control of additional territory. When Isis militants captured Mosul, Kurdish Peshmerga moved to secure nearby Kirkuk after national army and security forces fled the city.

The autonomous Kurdistan Regional Government (KRG) has long wanted oil-rich Kirkuk to be the capital of a future Kurdish state, although the city remains outside official KRG territory.