The leader of the armed wing of the Kurdistan Workers' Party (PKK) warned in an interview several weeks ago of a possible campaign of attacks by his Kurdish rebels in Turkey, the BBC said Monday.
The PKK denied involvement in two bomb attacks that killed 17 people in Istanbul on Sunday night, blaming "sinister forces".
Turkish Prime Minister Recep Tayyip Erdogan implicitly blamed the attacks on Kurdish separatists without specifically accusing the PKK by name.
The BBC showed Monday an interview with Murat Karayilan, the head of the PKK's armed wing, which it said it took weeks ago in the Qandil mountains region of northern Iraq.
"It's possible we'll start a campaign of attacks against economic and military targets in Turkish cities," Karayilan said, according to the BBC's translation of his comments.
"If their soldiers continue to attack us, we're prepared to do this."
The PKK is branded a terrorist group by Turkey, the United States and the European Union. More than 37,000 people have died since 1984 in attacks during its struggle for a Kurdish homeland in southeastern Turkey.