The clashes put a severe strain on a unilateral ceasefire declared by the Kurdistan Workers Party (PKK) rebels last December, but ignored by the government.
The regional governor's office in the city of Diyarbakir said that 90 PKK fighters and 27 troops died in clashes in the mountainous north of Diyarbakir province and in the neighbouring Bingol province.
"I am deeply saddened that 27 of our worthy sons were martyred in an operation by the Turkish armed forces," President Suleyman Demirel said.
Fighting between thousands of troops and a group of 200-250 guerrillas, recently arrived in Turkey from training camps in northern Iraq, began late last Friday. Clashes were still breaking out in the area, the governor's office said.
The rebel leader Abdullah Ocalan, believed to be based in Syria, called a ceasefire last December, but ordered his forces to fight back if attacked.
Eighteen rebels and three soldiers died in fighting in a wooded area on the border between Bingol and Tunceli provinces in clashes that began on Sunday as part of the anti-rebel drive.
Military officials said that it was unclear if those casualties were included in the total death toll. Eleven PKK fighters were also killed in separate clashes on Monday in the south-eastern provinces of Siirt and Mardin, the governor's office said.
More than 18,700 people have died so far in the rebels' fight for Kurdish autonomy or independence.
Mr Ocalan said he had called the ceasefire to give any new government a chance to solve the Kurdish problem after general elections last December.
Prime Minister Mesut Yilmaz's conservative coalition has promised to scrap emergency rule in 10 south-eastern provinces.
Security officials said the rebels' regional commander Semdin Sakik, known as "Fingerless Zeki" since he lost a thumb while firing a rocket, may be at the head of the group of guerrillas who infiltrated from northern Iraq.
Mr Sakik has been active in Tunceli since 1994, but spent most of the winter across the border.
Turkish forces failed to dislodge the rebels from their mountain camps in northern Iraq despite a cross-border push by 35,000 troops last year which lasted for six weeks. Tens of thousands of troops have been guarding the 330km (200-mile) frontier with Iraq in preparation for a possible spring guerrilla offensive.
Fighting inside Turkey usually increases in March and April when the snow melts in the mountains where the rebels are holed up. "With the coming of spring, they are coming down from the mountain tops and presenting themselves as easier targets," a commando officer at a security post in Tunceli province said.Reuse content