Figallo said yesterday that the request was "baseless" because there was no constitutional provision for tweaking the sentence.
"So there is no opinion to give; (the request) is completely baseless," he told a legislative panel hours after Fujimori attorney William Castillo confirmed a request had been filed.
An agronomist of Japanese descent, Fujimori was little known when he was elected president in 1990, defeating novelist Mario Vargas Llosa in an upset.
He initially gained immense popularity by rescuing the Peruvian economy, but used it to dissolve Congress, rewrite the constitution, and wage a bitter no-holds-barred counter-insurgency campaign.
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In 2009, Fujimori was sentenced to 25 years in prison for human rights violations committed during his presidency.
He is serving out his sentence at a police base in Lima where he is allowed visits from friends and family members but not the media.
His attorney maintains Fujimori is elderly, ailing and no threat to society.