Armed with firebombs and slings, Kurdish protesters clashed with Turkish police in two cities Tuesday and the main Kurdish party threatened to boycott the upcoming election because of a decision to bar some Kurdish candidates.

The ruling by the High Election Board was a serious blow to the pro-Kurdish Peace and Democracy Party, which is backing independent candidates in the June 12 national election in order to overcome a 10 per cent threshold for political parties to enter the 550-seat Parliament.

The election board's decision outraged party members and even drew criticism from Parliament Speaker Mehmet Ali Sahin from the ruling Justice and Development Party.

"It is a decision that has weakened the mission of Parliament," Sahin said. "It is not a decision that can be accepted by the country's democratic conscience."

Riot police clash with pro-Kurdish demonstrators during a protest in Istanbul on Tuesday. Osman Orsal/Reuters

Kemal Kilicdaroglu, leader of the main opposition party, said the Parliament should convene to find a solution and discuss lowering the threshold to enter parliament.

"If we believe in parliamentarian system, then a solution can be found," Kilicdaroglu said.

The pro-Kurdish party described the decision as a "political move" and a "blow to efforts to seek peace" in the southeast, where tens of thousands of people have lost their lives in a decades-long war between autonomy-seeking Kurdish rebels and Turkish troops.

"Kurds are trying to hold on to Parliament despite the 10 per cent barrier, despite all anti-democratic efforts, despite the doors being slammed on them," Sabahat Tuncel, whose candidacy was rejected, told Haberturk television in Istanbul.

The decision triggered a violent protest in eastern city of Van, where Kurdish protesters, shouting support for the imprisoned Kurdish rebel chief, tossed firebombs at several bank branches, Dogan news agency video showed. Two policemen were injured when their vehicle rolled over a makeshift roadblock.

Bengi Yildiz, a Kurdish lawmaker, told Turkish media that police used water cannons and tear gas to disperse hundreds of protesters Tuesday in the southeastern city of Diyarbakir.

The protesters in Diyarbakir had gathered outside a court to support some elected Kurdish mayors on trial for alleged ties to the rebels. The court on Tuesday again refused to accept hearing their defence in Kurdish language and defence lawyers walked out off Tuesday's hearing in protest.

About 400 protesters gather in Istanbul

About 400 Kurdish protesters also gathered in Istanbul's main Taksim square to protest the election board ruling.

The election board rejected allegations that it had political motives and said 12 candidates were removed from the list of candidates due to past convictions or a lack of official papers.

Gultan Kisanak, however, argued that her candidacy was blocked even though the local prosecutor's office confirmed she had no criminal record. Kisanak said she served time in prison after the 1980 military coup and was convicted for participating in a pro-Kurdish protest in 1990, but the statute of limitations had expired in both cases.

The election board also argued it was unaware of a court decision that reportedly gave two former Kurdish lawmakers, Hatip Dicle and Leyla Zana, their electoral rights back after serving a decade in prison for links to Kurdish rebels. Zana is a prominent Kurdish activist but the decision dashed her hopes to make a comeback to Parliament.

Explosion wounds two: report

Meanwhile, Turkey's state-run Anatolia news agency said a bomb explosion wounded two people near a police station in the country's south.

The report says police are investigating whether the homemade bomb went off prematurely, injuring two men who intended to hide and set it off. Anatolia says the explosion ripped off the right hand of one of the men.

The blast occurred Tuesday in the Mediterranean port city of Mersin, which has lately seen an increase in attacks by supporters of Kurdish rebels who are fighting for autonomy in the country's southeast.

Hundreds of thousands of Kurds have migrated to Mersin and other cities in the country's west to escape the fighting in the southeast. The conflict has killed tens of thousands of people since 1984.