The device, hidden behind a trash can, exploded in the town of Sehan in southern Adana province as "our security forces intervened to stop a banned protest, injuring six people, including two civilians, Anatolia news agency quoted Adana governor Huseyin Avni Cos as saying.

"Two police officers are in serious condition," the governor said.

The NTC news channel said police were moving to disperse a banned demonstration by supporters of the PKK at the time of the blast.

A surge of attacks by Kurdish rebels also targeting civilians are piling pressure on Turkey, which has threatened to launch an incursion into northern Iraq to root out rebel bases.

Turkish warplanes have bombed rebel bases in northern Iraq several times since August, killing between 145 and 160 rebels, according to the general staff.

The PKK, listed as a terrorist group by Ankara and much of the international community, took up arms in Kurdish-majority southeast Turkey in 1984, sparking a conflict that has claimed about 45,000 lives.