Turkish jets kept up bombing raids on Kurdish rebel bases in northern Iraq overnight, as the rebels confirmed that some Turkish troops crossed into Iraq, officials and media reports said on Friday.
Turkish war planes continued to take off from Diyarbakir, the regional capital of the mainly Kurdish southeast, to strike at Kurdish rebels who killed 24 soldiers in a string of coordinated attacks on Wednesday, local security forces said.
The Turkish army said on Friday that the air and ground strikes against the rebels are "mainly" in Turkey.
"While the majority of the land and air operations are in (Turkey), mainly in the Cukurca region, ground and air strikes are ongoing in a few points in northern Iraq across the border," the army said in a statement posted on its website.
A small group of specially trained Turkish troops crossed into Iraq from the villages of Yekmal and Bilecan on the Turkish side of the border and entered the Dola Sulo region in Haftanin, sources from the Kurdistan Workers' Party (PKK) said, Kurdish news agency Firatnews reported Thursday.
Gunshots and the sound of helicopters overhead were heard overnight in Turkey's Hakkari province near the border, an AFP photographer at the scene said.
The Turkish army on Thursday initiated "a large-scale land operation" with 22 battalions against the rebels in five separate spots inside and across the border, according to the general staff. The ground incursion is supported with air strikes, it said.
Around 10,000 soldiers took part in the operation, Turkish media reported Friday. Some 6,000 of them were special forces, the daily Sabah said.
The battalions comprise commando units as well as gendarmerie and special forces, the army has said, without specifying how many had entered Iraq.
"The air and land operation is under way," Prime Minister Recep Tayyip Erdogan told reporters right after the military announcement.
On Friday Erdogan is expected to meet with Iranian Foreign Minister Ali Akbar Salehi, who is on a surprise visit to Turkey after a string of coordinated PKK attacks caused Turkish uproar.
Turkish Foreign Minister Ahmet Davutoglu invited Salehi, the foreign ministry said in a statement carried by the Anatolia news agency.
Salehi will also meet with Davutoglu and President Abdullah Gul, who said Turkey would exact "a huge revenge" against the PKK for the attacks.
The loss of 24 soldiers was the worst death toll for the army since 1993, when 33 unarmed soldiers were killed in Bitlis province.
Since July, Tehran has been carrying out a major offensive against the Party of Free Life of Kurdistan (PJAK), which Turkey considers a branch of the PKK.
Clashes between the PKK and the army have escalated since the summer.
The PKK, listed as a terrorist organisation by Turkey and much of the international community, took up arms in Kurdish-majority southeastern Turkey in 1984, sparking a conflict that has claimed some 45,000 lives.