Turkey accuses Barzani and his administration of providing shelter and support to an estimated 3,000 PKK guerrillas.
Barzani denies the charges but says he will not turn over any Kurd to Turkish authorities. Turkish-Iraqi bilateral trade amounts to some $5 billion per year and oil from northern Iraq flows through Turkish pipelines.
TALKS
Rice holds talks with Erdogan and other top officials in the Turkish capital before heading to Istanbul for a meeting of foreign ministers from Iraq's neighbours and major powers that is sure to be dominated by tensions between Ankara and Baghdad.
She has promised "concrete action" and is prodding Iraq, particularly Kurdish authorities in the north, to close PKK bases and arrest leaders to prevent attacks.
"It's absolutely imperative that steps be taken to prevent such PKK attacks in future. Secretary Rice will be discussing this (in Turkey)," U.S. under secretary of state for political affairs Nicholas Burns told reporters in Vienna.
After talks with Barzani in northern Iraq, British Defence Minister Des Browne said firm and resolute action was needed immediately to constrain the PKK, but military action would be in nobody's interest and further dialogue was vital.
Iran's foreign minister arrived for an unexpected visit to Ankara on Thursday after talks in Baghdad. Maliki's government called on Iran to help them avert a Turkish incursion.
Erdogan is under tremendous pressure to act as the military and much of public opinion doubt Washington or Baghdad will crack down on the PKK and Barzani has little incentive to do so.
Analysts question Ankara's willingness to authorise a major incursion, saying Turkish leaders still hope their rhetoric will push U.S. and Iraqi authorities into acting against the PKK.
Turkey's large-scale incursions in 1995 and 1997 failed to dislodge PKK rebels from the Iraqi mountains. NATO's second largest army will want to avoid getting bogged down in difficult terrain as winter looms.
Ankara blames the PKK for the deaths of nearly 40,000 people since the group launched its armed campaign for an ethnic homeland in southeast Turkey in 1984. The United States and European Union, like Turkey, brand the group as terrorist.
