A Kurdish rebel commander threatened more attacks on Turkish targets on Wednesday, saying the guerrilla group would keep fighting until its demands for greater rights and autonomy are met, a pro-Kurdish news agency reported.
Kurdish rebels have escalated attacks throughout Turkey in recent weeks, saying Turkey has rejected calls for a dialogue. On Tuesday, a remote-controlled bomb attack on a bus carrying military personnel and their families, killed four soldiers and an officer's 17-year-old daughter. The deaths brought the number of soldiers killed in Turkey since Friday to 17.
A Kurdish militant group, the Kurdistan Freedom Falcons, which is linked to the rebels, claimed responsibility for the attack.
The agency Firat News quoted Cemil Bayik, a top commander of the Kurdistan Workers Party, or PKK, as saying: "It is not possible to end this struggle unless the Kurdish problem is solved... It is not possible to repress the guerrillas' capacity for action."
"Our movement's political strength and strength to launch attacks will continue as long as the Kurdish people's demands for freedoms continue to exist," Bayik, who is believed to be in northern Iraq, was quoted as saying.
Turkey last year declared it was taking steps toward granting more rights for Kurds in an effort to reduce support for the rebels and end the decades long fighting that has claimed the lives of some 40,000 people.
Kurdish rebels however, accused Turkey of ignoring demands for autonomy, freedom for imprisoned Kurdish rebel leader Abdullah Ocalan, an unconditional amnesty for rebel commanders and of refusing to allow Kurdish language education in schools.
Turkey firmly rules out dialogue with the PKK which is considered a terrorist organization by the United States and the European Union.
On Wednesday, police in Istanbul detained 27 people for questioning over the Istanbul bomb attack, the state-run Anatolia news agency reported, without citing sources. Istanbul Police Chief Huseyin Capkin confirmed that a number of people were rounded up but did not provide further detail.
The PKK had previously threatened to expand their war to cities in the west of the country. Authorities increased security across the nation, fearing new Kurdish rebel suicide attacks or bombings in tourist resorts and cities, as in the past.
PKK rebels move in an and out of bases in northern Iraq to stage hit-and-run attacks on Turkish targets. Around 4,000 rebels are based just across the border in Iraq and that about 2,500 operate inside Turkey, according to the Turkish military.
Turkish warplanes have carried out a series of retaliatory air raids on suspected Kurdish rebel hideouts across the border and troops have also crossed the frontier to hunt the rebels down.
Prime Minister Recep Tayyip Erdogan, addressing a southeast European leaders' summit, accused Europe of not sufficiently cooperating with Turkey in its fight against the PKK, which has been branded a terrorist organization by the European Union and the United States.
"In the past we have not received all of the help from some European nations as we would have liked," Erdogan said.
"The declaration of PKK as a terrorist organization is positive and I welcome that, but there were terrorists caught by you. How many of them did you return to us?" he said, in reference to suspected PKK militants arrested in European countries.
Associated Press Writer Erol Israfil in Istanbul contributed to this report.