Kurdish guerrillas killed 13 Turkish soldiers in an ambush in southeastern Turkey on Thursday - shortly after Kurdish MPs announced a breakdown in talks with the government, dpa reported.
The governor of Diyarbakir province, Mustafa Toprak, said seven other soldiers were wounded in the clash near the town of Silvan. Two of the seven was reported to be in a serious condition.
Seven guerrillas, presumed members of the Kurdistan Workers Party (PKK), were also killed in the shootout, the Turkish military said. It was the highest death toll of Turkish troops in the past three years.
Prime Minister Recep Tayyip Erdogan cancelled a trip to Istanbul and held an urgent meeting with leading Cabinet ministers, the chief of general staff, the commander of Turkey's paramilitary police and the head of national intelligence in Ankara.
The soldiers encountered the guerrillas in a forest while searching for three people kidnapped earlier this month, the Turkish military said in a statement. In the exchange, the PKK threw hand-grenades which started a forest fire and inflicted heavy casualties.
It was not clear whether the 13 soldiers were killed by the fire or the grenades.
Earlier Thursday, one of the newly-elected Kurdish nationalist parliamentarians told reporters that two days of talks with the ruling Justice and Development Party (AKP) and speaker of parliament had failed to persuade the 35 Kurdish MPs to take the oath of office.
The Kurdish parliamentarians, who belonged to the Peace and Democracy Party (BDP), had declined to take the oath when parliament opened on June 28 because one of their colleagues, Hatip Dicle, had been stripped of his seat by the National Election Board for having previously been convicted of spreading PKK propaganda.
Speaking on behalf of the BDP, Gultan Kisanak said the party had decided not to take part in the parliament's work.
Parliamentary Speaker Cemil Cicek said the timing of the ambush was significant. "Everybody must decide where he stands," Cicek told the press, "either with democracy or with the people filled with rage, hatred and bloodshed."
Governor Toprak said military operations were continuing in the area of the clash. The HaberTurk TV channel broadcast live pictures from the scene, showing smoke rising from the forest fire.
The head of Turkey's army, General Erdal Ceylanoglu, flew to the scene to take command of the operation.
The PKK first took up arms in 1984 with the aim of establishing an independent Kurdish state in southeastern Turkey. It has since modified its views, saying that it strives for Kurds to have equal rights with Turks in an autonomous zone of Turkey.