|A masked demonstrator poses with a banner for the outlawed PKK during protests in Istanbul in April [Reuters]
Kurdish separatists have claimed responsibility for an ambush on a police convoy in northern Turkey, and warned the country's government it faces a "great war" if it fails to enter "meaningful negotiations" after next month's elections.
Wednesday's attack in the northern province of Kastamonu left one policeman dead and another wounded.
"A retaliation attack was carried out by our militants on a police car that was part of a convoy...the attack only targeted police. It is not an attack on civilians or the prime minister," said a Kurdistan Workers Party (PKK) statement on the Firat news agency website.
The group's jailed leader, Abdullah Ocalan told Firat that "all hell would break loose" unless Ankara opened talks with Kurdish groups within six weeks, and within days of the country's June 12 parliamentary elections.
"June 15 is the deadline. Either a meaningful negotiation process will begin after June 15 or a great war will start and all hell will break loose," Ocalan said via his lawyers, Firat reported.
Earlier on Friday Turkish police arrested up to eight people over Wednesday's ambush in which gunmen opened fire on a police car escorting a ruling Justice and Development Party (AKP) campaign bus from an election rally by Prime Minister Recep Tayyip Edrogan in Kastamonu.
Erdogan had left the rally by helicopter before the attack occured. TRT news said eight people had been detained during police raids in Ankara, suspected of planning another attack.
Speaking to reporters after visiting the wounded officer on Friday, Erdogan said the attack bore the hallmarks of the PKK and accused the group of targeting his party, which is expected to win a third consecutive term in next month's vote.
"We knew that the separatist terrorist organisation would use these undemocratic methods ahead of the elections," he said.
The PKK ended a six-month ceasefire in February and there have been fears of rising violence before the election.
"This attack is a message to the AKP to withdraw its police who suppress Kurdish people. As all know, the police have carried out very harsh interventions on Kurdish people recently," the PKK statement said.
More than 40,000 people have been killed in a separatist conflict in southeastern Turkey since the PKK took up arms against the state in 1984.
PKK operations are generally focused on the mainly Kurdish southeast, but there had been prior warning of possible attacks in the Black Sea region.