Turkey has long complained over Kurdistan Workers' Party (PKK) rebels taking refuge in neighbouring northern Iraq and using the region as a springboard for attacks on Turkish targets as part of their 25-year separatist campaign.

In 2008, the three countries set up a three-way committe to enact measures against the PKK, listed as a terrorist group by Turkey, the United States and much of the international community.

"Within this trilateral framework, the United States is working with the government of Turkey and the government of Iraq... to ensure cross-border security and an end to PKK terrorism," General Jay Odierno said in a written statement upon arrival.

The general stressed that "broad-based solutions" were necessary to secure an end to the fighting.

"It is important that we develop a common understanding of the root causes of violence, so we can assist in determining political, economic and security measures that will contribute to increased security and safety of the Turkish and Iraqi people," he added.

Odierno is scheduled to meet Turkish chief of staff Ilker Basbug, Foreign Minister Ahmet Davutoglu and Interior Minister Besir Atalay on Wednesday.

In August, the Ankara government announced a series of steps to expand Kurdish freedoms with the hope of ending the PKK insurgency, but the drive has faltered amid a ban on the country's main Kurdish party, street protests and PKK violence.

The PKK picked up arms against Ankara in 1984 for self-rule in Kurdish-majority southeast Turkey, sparking a conflict that has claimed some 45,000 lives.