Turkish forces said they repelled a Kurdish rebel attack near the Iraqi border and President Abdullah Gul warned the PKK on Thursday that Turkey's patience was running out.
Ankara has massed as many as 100,000 troops along the mountainous border ahead of a possible cross-border operation to crush around 3,000 rebels of the Kurdistan Workers Party (PKK) who use northern Iraq as a launchpad for attacks on Turkey.
Iraqi, Turkish and U.S. diplomats have stepped up efforts to avert a large-scale Turkish incursion but Gul said Turkey would not tolerate more PKK attacks from Iraq.
"We are totally determined to take all necessary steps to end this threat... Iraq should not be a source of threat for its neighbors," Gul told an economic conference in Ankara.
"Although we respect the territorial integrity and unity of Iraq, Turkey is running out of patience and will not tolerate the use of Iraqi soil for the purpose of terrorist activities."
Public pressure on the Turkish authorities to act has grown since rebels killed 12 soldiers in clashes last weekend.
Turkish security sources have confirmed a series of sorties by warplanes and ground troops since Sunday into Iraqi territory, though Ankara has said it still hopes diplomacy can stave off the need for a full-blown ground invasion.
Turkish troops using tanks and artillery to beat off an attack by up to 40 PKK rebels late on Wednesday on a military post in Hakkari province near the border, security officials said.
After heavy clashes, the guerrillas withdrew into northern Iraq, taking with them an unknown number of dead and wounded, the officials said. One Turkish soldier was injured.
Early on Thursday, witnesses saw F-16 fighter jets taking off from the airport in Diyarbakir, the largest city of Turkey's mainly Kurdish southeast region. It was not known where the planes were heading.
An Iraqi Kurdish security official said a Turkish warplane had bombed a Kurdish village on Wednesday but gave no details of any damage.
In a visit billed by Turkish officials as "a final chance" for diplomacy, an Iraqi team led by Defense Minister General Abdel Qader Jassim and including members of northern Iraq's Kurdish administration was due in Ankara later on Thursday.
The Baghdad government has promised to shut down PKK camps but Ankara knows the central Iraqi government has little clout in the autonomous Kurdish north.
Turkish newspapers on Thursday accused Iraqi and Iraqi Kurdish leaders of dishonesty and unreliability for promising much and delivering virtually nothing.
They were especially angry with Iraqi President Jalal Talabani, a Kurd, whom Turkish officials quoted on Wednesday as saying Baghdad might hand over PKK rebels to Turkey. Talabani's office later denied he said this.
The United States, Turkey's NATO ally, is desperately keen to avert major Turkish military action in northern Iraq, fearing it would destabilize not only the most peaceful part of that country but potentially the wider region.
The State Department said Secretary of State Condoleezza Rice would visit Turkey on November 2-3 to try to reduce tensions between Turkey and Iraq.
Turkish Prime Minister Tayyip Erdogan is also due to meet President George W. Bush in Washington on November 5.
Rice told the House Foreign Affairs Committee on Wednesday she had told Erdogan in a phone conversation on Sunday that she took the situation "extremely seriously".
Ankara blames the PKK for the deaths of more than 30,000 people since the group launched its armed campaign for an ethnic homeland in southeast Turkey in 1984.
(Additional reporting by Evren Mesci in Ankara and Thomas Grove in Uludere)