The United States on Friday promised effective action against Kurdish rebels launching attacks on Turkey from northern Iraq, but cautioned Ankara against military moves that might destabilize the area.

U.S. Secretary of State Condoleezza Rice, visiting Turkey amid growing anti-U.S. sentiment, called the outlawed Kurdistan Workers Party (PKK) a common enemy. But she did not spell out what steps Washington was contemplating.

Ankara has warned it will carry out a major cross-border operation unless U.S. and Iraqi authorities fulfill pledges to crack down on an estimated 3,000 PKK guerrillas using northern Iraq as a base to carry out deadly attacks in Turkey.

Turkey, a NATO member with the alliance's second-biggest army, has sent up to 100,000 troops to the Iraqi border, backed by tanks, artillery and aircraft. But Iraq and the United States have urged Ankara to refrain from a major operation in an area that has so far been spared the worst of the violence in Iraq.

We have certainly been concerned that anything that would destabilize the north of Iraq is not going to be in Turkey's interests, it is not going to be in our interests and it is not going to be in the Iraqis' interests, Rice told reporters traveling with her.

But we understand the need to do something effective against this PKK threat, she said.

Rice began talks with Turkish Prime Minister Tayyip Erdogan, who is going to Washington next weeks for discussions with President George W. Bush on how to tackle the PKK.

Rice will also meet President Abdullah Gul and Foreign Minister Ali Babacan as she seeks to ease U.S.-Turkish tensions and dissuade Turkey from launching a cross-border operation.

Turkish-U.S. ties are at a low following a resolution passed by a U.S. congressional committee last month that called the 1915 massacre of Armenians by Ottoman Turks a genocide. Rice hopes to heal any rifts from that.

STRATEGIC RELATIONSHIP

It's an important strategic relationship, she said of Turkey, which is one of the main supply routes to U.S. troops in neighboring Iraq.

A recent poll by the Pew Research Center in Washington put the U.S. favorability rating in Turkey at 9 percent and found Turks see the United States as the single biggest threat to their nation's security.

Erdogan is under pressure to act as the military and much of public opinion doubt Washington or Baghdad will crack down on the PKK; nor do they expect firm action from Masoud Barzani, the head of the Kurdish semi-autonomous region of northern Iraq.

The subject on our agenda is an operation not a war. We hope that this operation will not be necessary, Erdogan said in a speech to officials from his ruling centre-right AK Party.

Turkish diplomats say the meeting with Bush will now be key to determining whether an incursion takes place or not in an area that has a complex mix of potentially antagonistic ethnic groups including Arabs and Turkmens as well as Kurds.

We really need to look for an effective strategy and not just one that will strike out somehow and still not deal with the problem, Rice said.

Analysts question Ankara's willingness to authorize a major incursion, saying Turkish leaders hope their rhetoric will push U.S. and Iraqi authorities into acting against the PKK.

Rice said short-term measures included better information sharing with the Turks and making it harder for the PKK to move around in northern Iraq.

Turkey plans economic sanctions that would target the PKK and groups providing them with support in northern Iraq, a move Rice said the United States could follow.

Rice said measures on how to deal with the PKK would be discussed at a meeting between herself and ministers from Turkey and Iraq on the sidelines of an Iraq neighbors' conference in Istanbul on Saturday.

Turkey accuses the Iraqi Kurdish authorities of providing shelter and support to the PKK in their region. Barzani denies helping the rebels but has yet to take action against them.

(Additional reporting by Hidir Goktas in Ankara)

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