The unilateral truce was never recognised by the Turkish army, which continued its campaign to crush the Kurdish separatists.
"The Turkish state has never complied with the ceasefire. Up until now their operations are continuing," said Zubeyir Aydar, president of KPC. "During the ceasefire they have not taken a step forward, but instead adopted a harder line."
He said some 500 fighters had been killed by Turkish forces in the last six years.
Truce at stake
The KPC is considered the successor to the Kurdistan Workers Party (PKK), which led a 15-year military campaign for self-rule in Turkey's mainly Kurdish southeast.
The campaign and ensuing conflict claimed an estimated 37,000 lives.
Following the capture of PKK leader Abd Allah Ocalan in 1999, the armed group announced a truce and an estimated 5,000 fighters withdrew into the mountains of northern Iraq.
KPC officials claim a 'hardening'
of Ocalan's prison conditions
Aydar said a "hardening" of Ocalan's prison conditions in Turkey and Ankara's failure to grant more rights to its large Kurdish population had also provoked an end to the truce.
Fighting in the region has been only sporadic over the past few years.
Turkey said the decision by the KCP to call off the truce "is clear proof that it is an armed terrorist organisation".
"Its discourse contains elements against Turkey's unity and security," said Turkish Foreign Ministry spokesman Namik Tan.
"What we expect of the terrorists is that they hand in themselves and their arms to security forces and be tried in court," he added.
He called on the US and the EU - which both include KCP on their list of terrorist organisations - to strengthen "cooperation with Turkey in the fight against international terrorism".