NATO chief Anders Fogh Rasmussen on Friday strongly condemned an attack by rebel Kurds on Turkish troops that left 13 soldiers dead. Seven Kurdish rebels were also killed in the attack Thursday in Diyarbakir province, southeastern Turkey, the deadliest ambush on troops in the rebel region for three years. \"I strongly condemn the terrorist attack in Diyarbakir province, in which 13 Turkish soldiers lost their lives and several others were wounded,\" Rasmussen said in a statement. \"Such heinous attacks have no justification. I express my heartfelt condolences to the families of those who were killed. NATO allies stand in full solidarity against the scourge of terrorism.\" The ambush took place during an army operation in a mountainous region known to be a stronghold of the outlawed Kurdistan Workers\' Party (PKK). The PKK, listed as a terrorist group by Turkey and much of the international community, took up arms in 1984, sparking a conflict that has claimed some 45,000 lives.