Ankara has not intervened militarily against IS jihadists trying to take the mainly Kurdish town of Kobane just across the Syrian border, to the fury of Turkey's Kurds.

Protesters in several cities in the southeast of the country with large Kurdish populations clashed overnight Wednesday to Thursday for the third night running with police, in the worst outbreak of such violence in years.

The latest death came in the southeastern province of Mardin when one protester was killed and half a dozen wounded in clashes with police Thursday.

The violence has sparked fears that the standoff over Kobane could endanger talks between the government and the outlawed Kurdistan Workers' Party (PKK) fighting an insurgency for self-rule in southeast Turkey.

Erdogan blamed the unrest on the "dark forces" seeking to sabotage the delicate peace process to end 30 years of violence that has claimed at least 40,000 lives.

"It's very obvious that this game is aimed at sabotaging the peaceful environment in the east and southeast as well as the peace process and our brotherhood," Erdogan said in his first comments on the unrest.

- 'We don't advocate violence' -

The PKK has largely observed a ceasefire since March last year. Despite a freeze in peace talks the process appeared to be making progress until the Kobane standoff.

Abdullah Ocalan, the jailed PKK leader, called after the protests for peace talks to move forward, warning of further unrest, a top Kurdish politician said.

Defying a curfew imposed by the army, hundreds of protesters took to the streets in southeast Turkey overnight and were dispersed by police using water cannon and tear gas, television said.

Meanwhile, clashes also took place in several districts of Istanbul with demonstrators throwing stones and anti-riot police responding with tear gas, an AFP correspondent said.

Violent protests were also reported in Ankara and the southern city of Mersin.

The clashes Wednesday night appeared less ferocious than the bloody violence on Tuesday when all the fatalities apparently took place.

At least 10 people were killed on Tuesday in Turkey's main Kurdish city of Diyarbakir, where supporters of an extremist Sunni Kurdish group had clashed with anti-IS Kurds.

Clashes broke out in a total of 27 provinces, Dogan news agency reported. Some 170 police officers were injured and 217 people were arrested across the country.

The situation in the daytime Thursday was comparatively calmer, with municipal workers sweeping up the rubble left after the Diyarbakir protests.

At Istanbul University Thursday, Turkish police detained 28 students following clashes between IS-supporters and anti-jihadist protesters.

Amnesty International on Thursday called on the government to "act to stop the spiralling violence" saying its actions "now will have far-reaching consequences."

"It is essential that the Turkish authorities act now to calm tensions with firm but rights-respecting policing and a commitment to investigate promptly the... deaths and scores of injuries of protesters," said Andrew Gardner of Amnesty International.