The protests appeared to have been triggered by a claim of responsibility for Tuesday's blast by a shadowy nationalist Turkish group, the Turkish Revenge Brigade, which vowed on its web site to avenge the killings of Turks by the separatist Kurdistan Workers' Party (PKK).

The authorities have played down the claim as an attempt for publicity, and even though no official statement has been made about the perpetrators, police sources have said that the suspicions fell on the PKK.

Officials said the bomb, which killed seven children and three adults and left 14 injured at a crowded park here Tuesday evening, went off while it was being carried to another location, apparently accidentally.

Groups of protestors, mostly young men, gathered at different spots across Diyarbakir, chanting slogans in favor of the PKK and accusing the government of covering up the perpetrators of the blast.

"The murderers should be found," they chanted, while some shouted "Revenge".

The demonstrators, who were not allowed to hold a march, burned tyres, overturned garbage containers and hurled stones at the security forces.

On several occasions, the police used pressurized water to disperse the protestors.

The PKK has a solid base in Diyarbakir, the largest city in the mainly Kurdish southeast and a hotbed of separatist Kurdish militancy.

Interior Minister Abdulkadir Aksu visited the city Thursday, but declined to give details about the probe until it is completed.

He promised that those responsible for the blast would be found and brought to justice "in the shortest possible time".

Kurdish politicians called the blast "a provocation," stressing that it occurred just a day after they appealed to the PKK to call a ceasefire.

The 22-year conflict between the PKK and the army has harmed Kurdish confidence in the state, especially due to serious human rights violations and rogue elements in the security forces acting outside the law.

In a landmark trial in June, two soldiers were sentenced to almost 40 years each for the deadly November bombing a bookstore in Semdinli town, owned by a former PKK militant.

The PKK, blacklisted as a terrorist group 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.