The Turkish army clashed with Kurdish rebels in the south east and northern Iraq in their deadliest battle in eight months, as the government pledged there would be no let-up.
Fifteen soldiers and at least 23 militants were killed, the military said yesterday. Twenty soldiers were wounded.
Prime minister Recep Tayyip Erdogan returned early to Ankara from an official visit to Turkmenistan to lead an emergency security meeting, and President Abdullah Gul cancelled a planned visit to France today.
"Whatever the cost, the fight will go on full force," Mr Gul told reporters before meeting with the chief of the military.
Outraged Turks demonstrated in the streets in several cities, politicians denounced the rebels, and images of grieving families of fallen soldiers covered the websites of almost all newspapers.
The Iraqi government, the European Union, Nato and the US Embassy in Ankara condemned the rebels and supported Turkey. But Iraq also called on Ankara to show restraint in its response.
The fighting was the deadliest since February, when Turkey staged a week-long ground offensive against guerrillas based in northern Iraq and claimed to have killed hundreds of them.
The military did not say whether Turkish soldiers crossed the border into Iraq on Friday, but said rebels attacked soldiers near a military outpost in Aktutun, Turkey, about six miles north of the Iraqi border, and Turkish warplanes, helicopters and artillery units pounded insurgent positions in northern Iraq.
Turkey's foreign ministry called the attack with heavy weaponry from northern Iraq "a grave situation" and called again on Iraq to capture the Kurdish rebels and work to prevent future attacks.
"We expect Iraq to fulfil its responsibilities," the ministry said.
Iraq's presidential council then said it would continue efforts with Turkey to prevent any more such aggression and end "the illegitimate presence of the gunmen on Iraqi territory".
Iraqi president Jalal Talabani had telephoned Mr Gul earlier yesterday and suggested resuming security talks, Turkey's presidential palace said. Mr Gul told Mr Talabani that Turkey expected Iraq to "immediately take necessary measures to stop these international terrorist acts against Turkish soil", the palace said.
Rebels of the Kurdistan Workers' Party, or PKK, have been fighting for autonomy since 1994 from bases in predominantly Kurdish south-eastern Turkey and northern Iraq.
Ahmed Deniz, a PKK spokesman in northern Iraq, said yesterday that the rebels had attacked a small Turkish army camp from four directions and that the fighting was continuing. He would not give any figures on rebel casualties and vowed to keep fighting.