Turkish warplanes continued to take off from Diyarbakir, the regional capital of the mainly Kurdish southeast, after the army's biggest losses at the hands of Kurdish rebels since 1993, local security forces said.

The Turkish army said Friday that the air and ground strikes against the rebels are "mainly" in Turkey, with a "few" in Iraq.

"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.

Cukurca, in southeastern Turkey's Hakkari province, is on the border with Iraq.

The latest cross-border ground incursion by Turkey into northern Iraq, an autonomous Kurdish region, was in February 2008, when the army struck against the Zap region.

A small group of specially trained Turkish troops crossed into Iraq, entering the Dola Sulo region in Haftanin, the Kurdish news agency Firatnews quoted sources from the Kurdistan Workers' Party (PKK) as saying Thursday.

Meanwhile gunshots and the sound of helicopters overhead were heard overnight in Cukurca, an AFP photographer in the city said.

He added that military helicopters flew from Cukurca to northern Iraq early Friday, while daily life in the town returned to normal after Wednesday's clashes left 24 soldiers dead and 18 wounded.

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.

"The air and land operation is under way," Prime Minister Recep Tayyip Erdogan told reporters right after the military announcement.

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 entered Iraq.

Iranian Foreign Minister Ali Akbar Salehi met Friday with his Turkish counterpart Ahmet Davutoglu, saying afterward: "Our first issue to discuss was terrorism. ... The PKK and the Party of Free Life of Kurdistan (PJAK) are the common problem of our countries."

Speaking at a televised joint press conference with Davutoglu, he urged "more serious cooperation" against the rebels.

Davutoglu said, for his part: "Our joint determination to fight against PKK and PJAK will go on in its strongest terms."

"From now on we will work together with a joint action plan until this threat of terror is eliminated totally," he said.

In a meeting closed to press, Salehi also met with President Abdullah Gul, who earlier said Turkey would exact "huge revenge" against the PKK for the attacks.

Salehi is also expected to meet with Erdogan.

Iraq, in an official statement on Thursday, pledged to cooperate with Ankara on security issues.

Nechirvan Barzani, a former prime minister of the Kurdish regional government, who paid a surprise visit to Ankara on Thursday, said after meeting with Davutoglu: "We strongly condemn this attack." He also met with Erdogan.

The string of coordinated rebel attacks dealt the worst blow to the army since 1993, when 33 unarmed soldiers were killed in Bitlis province.

Tehran has been carrying out a major offensive against PJAK, which Turkey considers a branch of the PKK, since July.

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.