Peru's prisons chief says former President Alberto Fujimori has been transferred to a private hospital to have precancerous lesions removed from his tongue for a fifth time.

Prisons chief Jose Perez says a date has not been set for Fujimori's return to the spacious quarters in a police station where he has been held the past five years.

The 74-year-old Fujimori was last operated on for the same thing in February 2011.

The ex-president is serving a 25-year sentence for overseeing death squad murders and for corruption during his government in 1990-2000.