(CNN) -- With Turkish officials under pressure to strike at Kurdish rebels in northern Iraq, U.S. President George W. Bush has told Turkey's president his administration will keep pressing Baghdad to clamp down on the rebels, the White House said Monday.
In a call to Turkish President Abdullah Gul, Bush expressed his "deep concern" over Sunday's killings of at least 12 Turkish soldiers by fighters from the Kurdistan Worker's Party, spokesman Gordon Johndroe told reporters. The group, known as the PKK, is considered a terrorist organization by Turkey, the United States and the European Union.
"The president reaffirmed our commitment to work with Turkey and Iraq to combat PKK terrorists operating out of northern Iraq," Johndroe said. "President Bush told President Gul that the United States will continue to urge the Iraqis to take action against the PKK."
The PKK announced it would observe a cease-fire starting Tuesday, an Iraqi Kurdish lawmaker told CNN. However, the rebels denied that claim. In a report from The Associated Press, the rebels said a cease-fire they declared in June was still in place.
With an estimated 60,000 Turkish troops stationed near the frontier, thousands of Turks rallied in Ankara and Istanbul in favor of a stronger crackdown on the rebels.
Bush's call is the latest step in what State Department spokesman Sean McCormack called a "full-court press" by Bush administration officials to avert Turkish intervention in northern Iraq's Kurdish territories, where the PKK has found refuge in its three-decade struggle for Kurdish autonomy.
Washington wants Iraqi Kurdish leaders to close PKK offices in their territory and stop the group from operating "as if they were some NGO," as a senior State Department official put it.
Turkey has complained that the United States and Iraq are not doing enough to stop cross-border attacks on southern Turkey, and last week Turkey's parliament overwhelmingly authorized military incursions into northern Iraq.
Bush's call to Gul was part of a combined campaign by U.S. officials to put intense pressure on Iraqi Kurdish leaders to crack down on the PKK and, along with Iraqi officials, to urge Ankara to hold off on any military operation, which could further destabilize the U.S.-backed government in Baghdad and disrupt supply lines for American troops.
Complicating the issue further has been the push in the U.S. House of Representatives for a resolution condemning the killings of Armenians by what was then the Ottoman Empire as "genocide." NATO ally Turkey has threatened to curtail U.S. access to bases on its territory if the resolution passes, and Bush repeated his opposition to the measure Monday, Johndroe said.
Bush's phone call followed weekend conversations between Secretary of State Condoleezza Rice and both Turkish Prime Minister Tayyip Recip Erdogan and Iraqi Kurdish leader Massoud Barzani. Rice and British Foreign Secretary David Miliband called Monday for Iraq to take "immediate steps" to prevent the rebels from operating on Iraqi soil.
"At a time when we are seeing real progress in the security situation inside Iraq and efforts to promote peace in the region, the Iraqi government must demonstrate its commitment to regional stability," the two diplomats said in a joint statement.
Rice and Miliband proposed a conference in Istanbul on Nov. 2 and 3 to discuss solutions to the crisis and urged the neighboring countries to support Turkey and Iraq in battling the PKK.
In addition, U.S. Ambassador Ryan Crocker met with Iraq's president, Jalal Talabani, late Monday at the Iraqi president's residence, his office said.
"President Talabani stressed the need to pursue dialogue and a peaceful solution to this issue in order to serve peace, harmony and progress in the region, and enhance bilateral relations between Iraq and its neighbor Turkey," Talabani's office reported.
Talabani, a Kurd, spent part of Monday meeting with officials in the three provinces that make up Iraq's Kurdistan autonomous region. As a result of the meetings, his office said, the PKK will announce a unilateral cease-fire.
Talabani called the pledge "a smart move" by the PKK, which he said has agreed to pull its fighters back from the border.
"They promised us they will suspend confrontation, and we are in talks with the Turks," he told reporters in Sulaimaniya.
And Iraqi Kurdish lawmaker Mahmoud Othman said Kurdish officials are working to persuade the PKK "to abandon the language of war and resort to dialogue." He said the cease-fire stemmed from pressure by Iraqi Kurdish leaders, including Talabani, to stop what Othman called "futile" military operations. E-mail to a friend
CNN's Ed Henry and Elise Labott in Washington, Jomana Karadsheh and Saad Abedine in Baghdad and Paula Hancocks in Ankara contributed to this report.
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