"I will not give a name, but a high-ranking PKK member was captured in Istanbul," Arinc said in a television interview Sunday.
Turkey, the United States and the European Union list the PKK as a terrorist organization.
Arinc did not give any details about when the PKK member was captured, the Dogan news agency reported.
"All operations conducted by security forces in the last three months have resulted in success," Arinc said.
"The Amanos mountains [on Turkey's southern border with Syria] have been cleared of terrorist entities.
"Other operations in urban areas in the southeastern provinces of Bitlis, Hakkari and Sirnak are continuing with success."