Six Turkish soldiers were killed by Kurdish separatists near the Iraq border, military officials said Tuesday. Militants from the Kurdistan Workers Party, or P.K.K., fired on an army unit Monday night, setting off a firefight that was joined by helicopters and land forces and that lasted until morning in the Cukurca area of Hakkari Province. The P.K.K. accuses the government of not being serious in its stated effort to increase the rights of Turkey’s nearly 12 million Kurds.