Joseph W. Ralston met his Turkish counterpart Edip Baser and was to hold talks with Foreign Minister Abdullah Gul later in the day.

Ralston has been tasked with coordinating joint efforts against the Kurdistan Workers' Party (PKK), listed as a terrorist group by both Turkey and the United States,

His visit follows harsh criticism by Prime Minister Recep Tayyip Erdogan of US and Iraqi inaction against the PKK and mounting calls at home for a cross-border military operation into northern Iraq.

Earlier this month, Erdogan accused Washington and Baghdad of failing to keep their promises to act against the PKK and, saying Ralston's appointment in August had produced no results, asked whether this was "a tactic" to distract Turkey.

He said that PKK offices in Iraq remained open despite an announcement by Baghdad in September that they would be closed and that some PKK militants infiltrating Turkey carried US-made weapons and bombs.

Ankara says northern Iraq has become a training ground for the PKK, where the group enjoys unrestricted movement and is easily able to obtain weapons and explosives for attacks on Turkish territory.

The US argues that it is swamped by violence in other parts of Iraq and says it is working to curb the PKK through non-military means such as cutting off its financial resources.

Washington has warned Turkey against a military incursion, fearing it may destabilise the relatively calm north and fuel tensions between Ankara and the Iraqi Kurds, who control the region.

Turkey and the Iraqi Kurds are already at loggerheads over the future of the ethnically volatile, oil-rich city of Kirkuk, which the Kurds want to incorporate into their autonomous region although the city is also home to Arabs and Turkish-backed Turkmens.

Ankara suspects the Iraqi Kurds of aiming to break away from Baghdad, which in turn, could embolden the PKK to step up its separatist campaign in adjoining southeast Turkey.

The PKK has fought for self-rule in the predominantly Kurdish region since 1984 in a bloody conflict that has claimed some 37,000 lives.

Ralston, who arrived here from Iraq, was expected to meet Chief of General Staff General Yasar Buyukanit on Wednesday before wrapping up his visit.