Fujimori was informed in hospital of the pardon by his son. (Photo: BBC)

Fujimori "suffers from a progressive, degenerative and incurable disease," according to a statement from current President Pedro Paulo Kuczynski's office. Fujimori was sentenced in 2009 after being convicted of authorizing the operation of a death squad responsible for killing civilians. He served as president from 1990 to 2000.

Opposition politicians allege that the president had promised supporters to free Fujimori in exchange for their backing. President Kuczynski denied the claim.