The UN chief on Saturday appealed for dialogue to resolve fears of a Turkish offensive against Kurdish rebels based in Iraq, and Iraqi Prime Minister Nouri al-Maliki pledged to work with his country's neighbors to fight terrorism. UN Secretary-General Ban Ki-moon and the Iraqi leader were in Istanbul for an international meeting on Iraq's future that has been overshadowed by the border tension, which escalated sharply over the last month amid a series of attacks by the rebel Kurdistan Workers' Party, or PKK. "The series of incidents along the border between Turkey and Iraq demonstrates the need for continuous engagement to address concerns," Ban said. "We recognize Turkey's security concerns." Ban said attacks by rebels based in Iraq were "clearly unacceptable."