Kurdish guerrillas attacked a military outpost in southeast Turkey overnight, triggering a clash in which 10 militants and three Turkish soldiers were killed, security sources said on Tuesday.
The assault was part of an upsurge in attacks on the armed forces since the rebels ended a 14-month ceasefire at the start of June. More than 80 soldiers have been killed so far this year, exceeding the death toll in 2009.
The increased violence has undermined an attempt by the government of Prime Minister Tayyip Erdogan to boost Kurdish minority rights and investment in the impoverished southeast in a bid to end a 26-year separatist conflict.
Military helicopters flew in troop reinforcements to search for the remaining Kurdistan Workers Party (PKK) rebels who launched the attack in the mountainous Semdinli district of Hakkari province, near the border with Iraq.Three soldiers were also wounded in the fighting.
The army operation was focused on the area around the Iraqi border, across which the militants frequently cross from bases in northern Iraq to attack the Turkish military. In response to the upsurge in attacks, the military has carried out air strikes on rebel targets in northern Iraq, where several thousand PKK guerrillas are based.
Negative impact on ties
The head of the Turkish armed forces, General Ilker Basbug, warned that the PKK presence in Iraq could harm ties with its neighbor and with the United States if action is not taken to curb the militants' activities in northern Iraq.
"The time has come and is passing for those responsible -- the people, institutions, states and formations in northern Iraq -- to do what is right," he was reported as saying in an interview with Star TV.
Ankara had often accused the Iraqi Kurds of tolerating and even aiding the PKK, but has recently shifted to a policy of seeking cooperation with them to curb the group.
The United States has also pledged support against the PKK, supplying its NATO ally with intelligence on rebel movements in northern Iraq to back up Turkish air raids against PKK hideouts in the region
Meanwhile, Turkey has repeatedly called for greater support from Iraq and the United States in its fight against the PKK, considered a terrorist organisation by Turkey, the United States and the European Union.
"The presence of the PKK in northern Iraq will have a negative impact on Turkish-Iraqi relations in the coming period. In a sense, it will negatively affect Turkish-U.S. relations," Basbug said.
The head of the General Staff estimated there were around 4,000 PKK fighters in the mountains of southeast Turkey and northern Iraq, compared with figures in the past of as many as 10,000 and an average of some 6,000.
Turkish intelligence is setting up a unit to capture three leaders of the group based in northern Iraq -- Murat Karayilan, Fehman Huseyin and Cemil Bayik -- Sabah newspaper reported.
Turkish special forces captured and jailed the PKK's leader Abdullah Ocalan in 1999 after forcing him to abandon his refuge in Syria.
More than 40,000 people have been killed in the conflict which began in 1984 when the PKK took up arms against the state with the aim of creating a separate Kurdish homeland.
The PKK, listed as a terrorist group by Turkey and much of the international community, has dramatically stepped up violence since its jailed leader Abdullah Ocalan said through his lawyers in May he was abandoning efforts to seek dialogue with Ankara.