The ground incursion into Iraq came after Turkish Prime Minister Recep Tayyip Erdogan vowed to fight the Kurdistan Workers Party (PKK) "to the end" and PKK spokesman Ahmed Denis hit back with a threat to attack cities across Turkey if the army did not halt its policy of confrontation.
Iraqi Foreign Minister Hoshyar Zebari, himself a Kurd, criticised the "unilateral" Turkish action and called on Erdogan's government to return to peaceful efforts to woo Turkey's large Kurdish minority away from violence.
By morning, the troops had advanced 10 kilometres (six miles) intoIraqi territory in the Qandil mountains where the rebels maintain a networkof rear bases in their 26-year-old armed campaign for self-rule insoutheastern Turkey, the Iraqi Kurdish security official said.
Turkish troops were operating in the mountains north of the town of Sidikan in Arbil province, one of three that make up the Kurdish autonomous region of northern Iraq, the official said.
Turkish fire killed a 15-year-old girl and wounded her mother andtwo-year-old brother in Khwakurq village, Sidikan district commissionerAhmed Qader told AFP.
As Turkish forces advanced into Iraqi territory during the nightthey killed another three people, a security official said, withoutspecifying whether the dead were civilians or PKK fighters.
Inside Turkey, the rebels kept up their attacks, killing one soldierand wounding another, bringing the military's losses in the past twodays to 12, Turkey's Anatolia news agency reported.
The new casualties came as the Turkish premier joined otherdignitaries in the eastern city of Van to honour the 11 soldiers whodied on Saturday -- the bloodiest single day for the army since 2008.
"We are not going to slide into defeatism... we are going fight on to the end," Erdogan said at the televised ceremony.
The death toll prompted indignation among ordinary Turks, with manycultural and sporting events cancelled in mourning. Around 1,000demonstrators gathered in Istanbul, chanting: "An eye for an eye."
On Monday morning, Turkish President Abdullah Gul is to chair ameeting of top political and military chiefs to discuss the upsurge inviolence, Anatolia news agency reported.
Last year, Erdogan had announced a new policy of boosting Kurdish freedoms and investment in the country's impoverished southeast.
But it has faltered amid an opposition outcry that Ankara is bowingto the PKK, as well as persistent rebel attacks and a judicialonslaught on Kurdish activists.
The Iraqi foreign minister called for a return to the previous policy.
"This initiative is a wise one and needs to be embraced, enhanced and translated into action as the best solution for this age-old problem," Zebari told AFP in an interview.
"Of course we do not condone or support any cross-border terroristattacks by the PKK," he stressed, adding that nonetheless "no countryshould resort to unilateral action."
Zebari said he feared Turkey was stepping up its incursions and airraids as the clock ticks down to an August 31 deadline for Washingtonto pull out 38,000 of its remaining 88,000 troops in Iraq.
"I personally believe the reason they are escalating these attacksnow is to test the will of the Iraqi government, and also the Americanforces, as a prelude to the withdrawal of US combat forces in August,"Zebari said.
"We are capable of filling the vacuum and we will not allow any other countries to step in to fill that vacuum."
Sunday's Turkish ground incursion was the second in five days andwent far deeper than the previous incursion on Wednesday when troopsadvanced just a few kilometres (miles) before withdrawing.
The conflict with the PKK, blacklisted as a terrorist organisation by much of the international community, has killed more than 45,000 people since it broke out in 1984, according to the Turkish army.