Ocalan is serving a life-in-prison sentence at the Imrali island prison. Imprisoned since the 1990s, Ocalan was the only inmate there until five other prisoners were sent to the island facility in 2009.
Turkish daily newspaper Hurriyet reported Friday that by June a new facility on the island would house more inmates, including four female members of the militant Kurdistan Workers' Party, known by its Kurdish language initials PKK.
A Justice Ministry statement published by Today's Zaman said there was no validity to the report.
"Construction work on Imrali is out of the question," the ministry said. "The claims in the news report do not reflect the truth."
Ocalan and Turkish authorities negotiated a settlement whereby PKK members would abandon Turkish territory. A small number of armed separatists crossed the border into Iraq early this month.