Kurdish residents take part in a protest against the recent Turkish air strikes at the border area between Turkey and Iraq, in Sulaimaniya city, 260 km (161 miles) northeast of Baghdad, Dec 30, 2011. Turkish rights groups called on Friday for a UN-sponsored investigation after Turkish warplanes killed 35 villagers in an air strike targeting Kurdish rebels on the Iraqi border that the government has called an operational mistake.[Photo/Agencies]

ANKARA - Turkish leaders Friday offered condolences to families of a military airstrike incident on the border with Iraq which killed 35 civilians, adding that investigation was going on, local media reports said.

Defining the incident as "unfortunate and saddening", Turkey's Prime Minister Recep Tayyip Erdogan said "we will do what we have to do at the end of the investigation."

Turkish military jets bombed a group of people approaching its border from Iraq Wednesday night in accordance with intelligence that the rebel Kurdish Workers' Party (PKK) was planning to attack military outposts after their recent losses, but only to find later the 35 dead were Turkish diesel smuggling peasants.

In a statement released Friday, the Turkish Armed Forces offered condolences for families of the 35 people who were mistakenly killed by military airstrikes near the Turkish border in northern Iraq.

"We wish God's mercy upon our citizens who lost their lives in the incident that took place on the night of Dec 28, 2011, and we also convey our condolences to their families," the military statement said.

There was a four-hour footage regarding the military operation, said the Turkish prime minister, adding that the Turkish Armed Forces together with the other concerned departments were investigating the incident.

On Friday, Turkish President Abdullah Gul also said the bombing incident was "a very unfortunate" one given all of the people who were killed in the bombing, were civilians.

The General Staff said the bombed area was frequented by the PKK members. Listed as a terrorist group by Turkey, the United States and the European Union, the PKK took up arms in 1984 to create an ethnic homeland in southeastern Turkey. More than 40,000 people have been killed in conflicts involving the PKK during the past over two decades.