"Kurdish forces have nothing to do with the blast," said a statement quoted by the Firat agency, widely regarded as the mouthpiece of the separatist Kurdistan Workers' Party (PKK).

The bomb, hidden in the saddle of a bicycle, exploded Friday morning near a bus stop in the centre of Diyarbakir often used by soldiers. One of those injured was a soldier.

"The way the incident happened and the type of explosive used indicates who did it," Interior Minister Osman Gunes said, in an apparent reference to the PKK, which has notably stepped up attacks this year.

He said a detailed statement would be made after the police completed their investigation.

The Turkish army has launched a large-scale crackdown against the PKK in the east and southeast and amassed troops at the border with Iraq, where the militants take refuge.

The PKK, listed as a terrorist organisation by Ankara and much of the international community, took up arms for Kurdish self-rule in the southeast in 1984. The conflict has claimed more than 37,000 lives.