By Seyhmus Cakan
DIYARBAKIR, Turkey (Reuters) - Police fired teargas and water cannon on Sunday to disperse thousands of protesters in Diyarbakir, the main city in Turkey's Kurdish-dominated southeast, during demonstrations across the country to pressure the government to carry out reforms.
Turkey's main pro-Kurdish Peace and Democracy Party, the BDP, had called for marches in at least three major cities, to launch a summer of protests against what it sees as a lack of commitment by Ankara to a peace process with Kurdish militants.
The Kurdish unrest comes after weeks of unrelated anti-government protests in Istanbul, Ankara and other cities in which four people have died and thousands have been injured.
Security forces killed an 18-year-old man and wounded 10 others when they fired on a group protesting against the construction of a gendarmerie outpost in the Kurdish-dominated southeast on Friday.
It was the most violent incident since a March ceasefire called by the Kurdistan Workers Party's (PKK) jailed leader Abdullah Ocalan and threatens to derail the nascent peace process between the rebels and the state.
Around 3,000 protesters, including BDP politicians, gathered in the center of Diyarbakir on Sunday evening but the crowds were prevented from marching through the city by riot police.
Some masked protesters threw percussion bombs at the police, who responded by firing teargas and water cannon, sending the crowds fleeing into the backstreets, a Reuters witness said. While most protesters dispersed, some threw rocks at the police.
Earlier in the day, a few hundred protesters clashed with police further east in Cizre district of Sirnak province, which borders both Syria and Iraq. The protesters burned tires and closed a main road while some threw firebombs at police who also responded with water cannon and teargas.
Separate protests in the city of Mersin on the eastern Mediterranean coast passed off peacefully.
Marches were expected in Diyarbakir, Mersin and Adana. Diyarbakir is the largest city in the southeast and Mersin and Adana further west have large populations of Kurdish migrants.
The separate anti-government unrest mainly in the west has largely died down over the past week, but on Sunday tens of thousands of anti-government protesters teamed up with a planned gay pride march in Istanbul. Crowds were stopped by riot police from entering Istanbul's Taksim Square, the center of previous protests, but the atmosphere appeared peaceful.
Around 10,000 people marched on Taksim on Saturday. The protest became partly one of solidarity with the Kurds after Friday's killing.
Turkey's Kurds have largely stayed away from the anti-government demonstrations which began at the end of May, and Prime Minister Tayyip Erdogan has tried to reassure them that the unrest will not harm the peace process.
But the renewed Kurdish unrest threatens to exacerbate the effects of the anti-government protests that have emerged as the biggest public challenge to Erdogan's 10-year rule. He has dismissed protesters as pawns of Turkey's enemies and has called supporters to back his party in municipal elections next year.
PKK militants began withdrawing from Turkish territory to bases in northern Iraq last month as part of a deal between the state and Ocalan, imprisoned on an island south of Istanbul since 1999, to end a conflict that has killed 40,000 people.
The BDP said the withdrawal was continuing successfully and the process had entered a second stage during which Ankara needed to broaden the rights of Kurds, who make up some 20 percent of the 76 million population.
Sunday's protests called for a halt to the construction of military outposts in southeastern Turkey, the release of political prisoners, education in Kurdish, lowering of the threshold of 10 percent electoral support required to enter parliament, and the release of Ocalan.
The BDP said it had presented to the government a 25-article proposal on which action needed to be taken urgently.
Erdogan said the process had still not entered the second stage as only 15 percent of PKK fighters had so far left Turkey. The BDP says at least 80 percent of the militants have either left Turkey or are en route to their bases in northern Iraq.
The PKK, designated a terrorist group by Turkey, the United States and European Union, took up arms against the state in 1984 with the aim of carving out a Kurdish state, but subsequently moderated its goal to autonomy.
(Additional reporting by Ece Toksabay in Istanbul; Writing by Jonathon Burch; Editing by Peter Graff)