Former Peruvian President Alberto Fujimori's chief doctor says he has been hospitalized for surgery to correct lesions on his tongue.

Dr. Alejandro Aguinaga tells The Associated Press that Fujimori entered a hospital Sunday. It will be the fourth time since 1997 that he has undergone such an operation.

Aguinaga says the procedure is scheduled for Monday morning.

The 71-year-old former leader is serving a 25-year jail sentence for killings and kidnappings by security forces during his presidency.

Fujimori ruled Peru with an increasingly iron fist from 1990 until 2000, when his government collapsed amid a bribery scandal.

In 2005 he left exile in Japan and traveled to Chile, where he was arrested and extradited to Peru.