The imprisoned leader of Turkey's main Kurdish rebel group has warned his forces will unleash a "big war" after national elections if Turkey refuses to negotiate to end the decades-old conflict.

Guerrillas claimed responsibility Friday for a deadly attack on a convoy that had just left a campaign rally held by the prime minister.

Ocalan's threat is expected to escalate tensions in the Kurdish-dominated southeast, where frequent clashes and violent protests have undercut reconciliation efforts.

"Either after June 15, a meaningful negotiation begins, or a big war starts, doomsday comes," the pro-Kurdish Firat agency website cited Ocalan as saying in a message delivered by his lawyers. Turkey holds elections on June 12 and final results are expected to take several days.

Ocalan remains a powerful symbol for his fighters, who revere him with a personality cult. Turkish leaders have confirmed communication between some state officials and Ocalan to seek a solution to end the fight by autonomy-seeking Kurdish rebels. But they refuse to negotiate with the rebels, who are branded as terrorists by Turkey and the West.

Aysel Tugluk, a former Kurdish lawmaker, had issued a similar ultimatum to the government, saying: "I hesitate to put it into words, but bad things will happen."

The comment angered Turkish leaders, who accused the Kurdish politicians of seeking to incite violence.

On Friday, pro-Kurdish politicians announced their election program, including autonomy in the largely Kurdish southeast and education in schools in their mother tongue. Those demands have been denied by Turkey on grounds that they would divide the country along ethnic lines.

Meanwhile, the rebel Kurdistan Workers' Party, known as PKK, claimed responsibility for a deadly attack on a police vehicle that was escorting an election convoy of Prime Minister Recep Tayyip Erdogan's party in northern Turkey. The statement, distributed to media in an email, said the attack was "aimed against the police vehicle only" and was not targeting Erdogan or civilians

Wednesday's attack in Kastamonu province left one policeman dead and another wounded.

Erdogan had left an election rally in Kastamonu by helicopter but journalists and party officials were returning to the capital Ankara in the convoy.

The attack came hours after clashes at funerals for seven Kurdish rebels on Wednesday in the southeast where tensions still run high.

Police on Friday raided homes of dozens of Kurds and detained them for attacking the police with firebombs and stones in demonstrations in the cities of Hakkari and Diyarbakir in recent days, the Anatolia news agency said.