Turkish Black Hawk helicopters have been flying into Iraq
The Turkish army says it has killed 41 more Kurdish rebels in the most recent clashes of its incursion in north Iraq.
Two Turkish troops also died in the fighting that brought the toll of rebels killed to 153 since Thursday, a statement on the army website said.
A Kurdish news agency said that Kurdistan Workers’ Party (PKK) rebels had forced the Turkish army to retreat in some areas.
The Iraqi government has urged Turkey to withdraw its forces.
But a spokesman for the Turkish government spokesman said Turkey had the right to defend itself against attacks launched from northern Iraq and operations would continue for as long as necessary.
The new fighting has prompted the Turkish president to postpone an African trip.
The army targeted about 30 PKK shelters during the fourth day of heavy shelling, destroying weapons and equipment, according to the army website.
Clashes between ground troops were also continuing.
“Terrorists trying to flee the region under our troops’ control suffered heavy losses under fire from close quarters overnight,” according to the statement by the Turkish army’s general staff.
Retreating rebels had set booby traps under dead bodies and planted mines on escape routes, the military said.
Earlier, the army had released footage of helicopters taking off from an unnamed military base in the south.
It is not clear where or when the footage was recorded, but Iraqi Kurd officials say Turkish forces struck PKK positions about 20km (12 miles) from the border.
The Associated Press news agency reports that the sound of artillery fire could be heard in the border town of Cukurca.
Seventeen Turkish troops have been killed since the fighting started and funerals attended by military commanders and top politicians have been taking place in border towns.
The Turkish authorities launched the cross-border attack on Thursday night, after accusing the Iraqi government of failing to stop the PKK from using the area as a safe haven.
Washington has called on Turkey to keep its campaign in Iraq – another US ally – as short as possible.
Turkish President Abdullah Gul was due to begin a four-day trip to Tanzania, the Democratic Republic of Congo and Congo on Tuesday.
A presidential spokesman told AFP news agency that the visit had been postponed because “the president wished to be in Ankara while the operation is still under way”.
More than 30,000 people have been killed since the PKK began fighting for a Kurdish homeland in south-eastern Turkey in 1984.
The US, the EU and Turkey regard the PKK as a terrorist organisation.