A statement posted on a PKK web site said Wednesday's attack in Diyarbakir, the largest city in the predominately Kurdish southeast, was a "successful action" by the group's militants.

The police bus came under fire just as parliament in Ankara extended by a year the government's mandate to order cross-border military action against PKK hideouts in neighbouring northern Iraq.

The police have detained nine people in connection with the incident, among them three alleged PKK militants believed to have taken part in the attack.

The army has stepped up operations against the PKK -- both inside Turkey and in northern Iraq -- since October 3 when rebels crossing from rear bases across the frontier assaulted a Turkish border outpost, killing 17 soldiers.

The PKK, listed as a terrorist group by Ankara and much of the international community, took up arms for Kurdish self-rule in the southeast in 1984, sparking a conflict that has claimed about 44,000 lives.