Kurdish rebels stormed a Turkish army post on the Iraq border Sunday, triggering fighting that killed 22 people in the latest clash since Ankara launched a major offensive against the outlawed PKK.
Prime Minister Recep Tayyip Erdogan condemned the attack as a "dastardly" act and vowed to bring the rebels in line.
Six soldiers, two village guards and 14 Kurdish rebels were killed following the assault on an army post in a village in the southeastern province of Hakkari, the local governor told the Anatolia news agency.
Three of the slain rebels were women, said governor Orhan Alimoglu.
Another 15 soldiers, one village guard and five civilians were wounded, according to a statement from the governor's office cited by Anatolia.
The rebels from the Kurdistan Workers' Party (PKK) launched simultaneous assaults on three border posts but the casualties occurred at a post in the village of Gecimli, the private NTV television station reported.
It was the deadliest clash since June when fighting between Turkish soldiers and Kurdish rebels left 28 people dead following a similar attack on an army post in the same region.
Mr. Erdogan, in a statement posted on the prime minister's office website, denounced Sunday's attack as a "dastardly" act and said: "Terror is doomed to failure ... sooner or later."
In a stark warning, Mr. Erdogan also said Turkey had the strength to bring into line not only the PKK but also "hostile countries and environs that hold in their hands the terrorist organisation's strings." He did not name those countries.
A series of similar assaults against troops in the Kurdish-dominated southeast prompted the army to launch an all-out offensive against PKK bases in the area last month.
The Turkish ground and air operation, one of the biggest in years, is focused on the town of Semdinli, in Hakkari province, and NTV television said about 2,000 troops are involved.
Some 115 Kurdish insurgents have been killed so far in the ongoing operation launched on July 23-24 in Semdinli, Interior Minister Idris Naim Sahin told Anatolia, adding that security forces were taking measures to prevent PKK members from fleeing to northern Iraq where they are holed up.
The PKK, considered a terrorist organisation by Turkey and much of the international community, took up arms in the southeast in 1984, sparking a conflict that has claimed some 45,000 lives.
Turkey's latest offensive against the PKK comes as Kurds in northern Syria are reported to have taken control of some regions as fighting escalates in the uprising against the rule of President Bashar al-Assad.
Mr. Erdogan has accused Damascus of giving Kurdish rebels a free hand in the north of the country and warned that Ankara would not hesitate to strike "terrorists".
Ankara claims some of the Kurdish rebels in Syria were forced to move there from hideouts in mountainous zones of northern Iraq after the Turkish army carried out several air strikes in the area.
The reported control of northern Syria by the Democratic Union Party (PYD), the PKK's Syrian ally, has pushed Ankara to take diplomatic and military steps to neutralise what it sees as any potential threat.
Turkey has massed a convoy of tanks, weapons and ground-to-air missile batteries on the border with Syria and staged military drills, which have been seen by the media as a show of force against Damascus.
Ties between one-time allies Ankara and Damascus have soured since Mr. al-Assad's regime launched a brutal crackdown on dissent in March last year.
Relations hit an all-time low after a Turkish fighter jet was brought down by Syrian fire in June, killing its two pilots and leading Ankara to brand Damascus a "hostile" opponent.
Damascus claims that Ankara is supporting "terrorists" to bring down the Syrian regime, referring to the Free Syrian Army of defecting soldiers which has a base on Turkish soil near the border.
Last week, Foreign Minister Ahmet Davutoglu visited northern Iraq for talks with Kurdish leader Masoud Barzani about the situation in northern Syria.
"The new Syria should be free of any terrorist and extremist group or organisation," the two said in a rare joint statement.
Although Turkey has built ties with the Kurdish regional government in the north of Iraq, Ankara is opposed to the idea of a separate Kurdish state.