DIYARBAKIR (AFP) - Turkish warplanes killed 35 people in an air strike on the Iraq border, officials said Thursday, in an attack which a pro-Kurdish political party described as a "massacre" of civilians.

Turkey's military command said it launched an air strike on PKK militants after an intelligence drone spotted a group of people moving toward its sensitive southeastern border under cover of darkness late Wednesday. Turkey's main pro-Kurdish Peace and Democracy Party (BPD) said the planes bombed a group of villagers from the Kurdish area of the southeast who were smuggling sugar and gas across the border. BDP leader Selahattin Demirtas called the attack a massacre, saying all the victims were civilians.

  Turkey's ruling party admitted that an air strike could have been a blunder, targeting local villagers instead of Kurdish separatist guerrillas.

"According to initial reports, these people were smugglers and not terrorists," Huseyin Celik, vice-president of the governing Justice and Development Party (AKP), said.

"If it turns out to have been a mistake, a blunder, rest assured that this will not be covered up," he told reporters, adding that it could have been an "operational accident" by the Turkish military.

"In the name of my party I would like to express our shock and sadness," he said, while calling on the public to await the results of an investigation.

But Ankara's joint military command said in a statement that its jets bombed an area inside Iraq "regularly used" by PKK rebels.  "The area where this happened is called Sinat-Haftanin, in northern Iraq, where there is no civilian population, and where the terrorist organisation has bases," the military said in a statement, referring to the outlawed Kurdistan Workers' Party (PKK).

The governor's office in Sirnak province said "35 people were killed and another person wounded in an aerial operation" and said an investigation was under way. "A crisis centre has been set up in the area and prosecutors and security officers have been sent" to the southeastern village of Ortasu near where the air strike took place, Governor Vahdettin Ozkan said. Ertan Eris, a local BPD councillor, told pro-Kurdish Roj TV from the scene of the bombing that the dead were among a group of up to 40 people, ranging in age from 16 to 20, who were engaged in cross-border smuggling.