At least 14 people were killed as pro-Kurdish protests raged across Turkey Wednesday over the government's failure to act against militants attacking the majority-Kurdish Syrian border city of Kobane.

The disturbances are the worst outbreak of such violence in years and risk derailing Turkey's peace process with the Kurds.

In a move unprecedented since the deadliest days of the Kurdish insurgency in the 1990s, the army was deployed to impose a curfew in several cities in the east.

The violence was concentrated in the mainly Kurdish southeast but also flared in Istanbul, Ankara and other cities, with empty buses firebombed and protesters hurling stones at police.

The ruling Justice and Development Party (AKP) government has so far not intervened militarily against Islamic State (IS) militants trying to take Kobane, to the fury of Turkey's Kurds.

Eight of the deaths came in Turkey's main Kurdish city of Diyarbakir, where the most intense rioting took place overnight Wednesday, a local security official told AFP.

Five of these deaths were blamed on clashes between Kurdish activists and supporters of Islamist groups in the southeast who are sympathetic to IS.

The clashes caused extensive damage in the city with shop fronts burned-out and buses set on fire.

Two people were reported killed in Mardin, two in Siirt, and one in Batman and another in Mus, all cities in the southeast of Turkey with large populations of Kurds. Further protests were planned for Wednesday.

The Turkish army has been deployed on the streets of the cities of Diyarbakir, Mardin and Van to enforce a curfew.

In Diyarbakir, Turkish troops and tanks were patrolling the city of 1.5 million people with the streets deserted after the night of violence, an AFP correspondent reported.

'Peace under threat'

The world's largest stateless people, Kurds are spread across Turkey, Iraq, Iran and Syria. Kurdish militants have waged a deadly insurgency for three decades for self rule in Turkey.

However, a peace process with the Turkish government appeared to be making progress until the Kobane standoff, and the latest protests threaten to derail the talks entirely.

"We will never tolerate vandalism and other acts of violence aimed at disturbing the peace," Deputy Prime Minister Yalcin Akdogan said in comments broadcast on state television.

"Attempts at violence and harm threatening the peace of our people will never be taken lightly," he added.

Schools were closed in Diyarbakir and flights were cancelled, reports said. The protests first broke out on Monday night but Tuesday's clashes were more severe.

Police also used tear gas and water cannon to disperse angry pro-Kurdish protests in Istanbul and Ankara.

In Istanbul, 98 demonstrators were arrested and dozens injured, Turkish television reported. Eight police were also injured.

The violence even spread outside Turkey's borders, with street clashes between hundreds of Kurdish and Islamist supporters in Germany's northern port city of Hamburg leaving 23 people wounded overnight.

In one act that enraged secular Turks, Kurdish demonstrators in Mardin set fire to a statue of the secular founder of modern Turkey, Mustafa Kemal Ataturk.

Selahattin Demirtas, the co-leader of the People's Democratic Party (HDP) which first called for the protests, condemned the burning of Turkish flags and attack on the Ataturk statue.

The outlawed Kurdistan Workers Party (PKK), which battled Turkish forces since 1984 in an insurgency that has claimed 40,000 lives, has largely observed a ceasefire since March last year.

But jailed PKK leader Abdullah Ocalan said in a message relayed by his brother from his prison on the island of Imrali on the Sea of Marmara that the government had until mid-October to show it was serious about the peace process.

"Peace under threat," headlined the Hurriyet daily above an apocalyptic picture of vehicles on fire in the protests.

Kurds, who make up from 15 to 20 percent of Turkey's population and are its largest minority, have been particularly irked by the reluctance of the authorities to allow Turkish Kurds to cross the border to fight Islamic State jihadists.

The government has parliamentary authorisation to use the military in Syria but says it will only send in troops if there is a coordinated international effort to oust President Bashar al-Assad.