"The response... must be very strong," Bahoz Erdal, a Kurdistan Workers' Party (PKK) leader, was quoted as saying by the Firat news agency, considered a PKK mouthpiece.

"If they want to wipe us out, our youths should make life in the cities unbearable... Kurdish youths should unite... and burn hundreds of cars every night," he said.

"This war will burn everyone. We are not against the Turkish people but this is the reality of war."

A little-known group called Komalen Ciwan and described by Firat as a Kurdish youth organisation joined the call, urging violence not only in Turkey but Europe, where large numbers of Kurdish immigrants live as well as in Iran, Iraq and Syria, which have their own Kurdish communities.

"The youths who live in Turkey must turn Turkish cities into hell," Firat quoted the group as saying.

Kurdish youths "must transform... cities in Syria, Iran, Iraq and Europe into hell... If this (northern Iraq) turns into a fire zone, so must other places," it said.

Turkish troops crossed into northern Iraq Thursday evening in the largest cross-border offensive in years against PKK hideouts in the region, bombing rebel positions and fighting the militants on the ground.

At least 112 rebels and 15 soldiers have been killed so far, according to the Turkish military.

The PKK, listed as a terrorist group by Ankara and much of the international community, has waged a bloody campaign for self-rule in mainly Kurdish southeast Turkey since 1984. The conflict has claimed more than 37,000 lives.