Kuczynski acknowledged the anger, but said that the decision was based on humanitarian grounds.

However, the protesters had none of it, who shouted, "no to the pardon".

Protesters even claimed that the former President has been pardoned after a deal was reached with the incumbent government, which has been refuted by the latter.

Fujimori, 79, is serving a 25-year prison term.

He was convicted in 2007 to a six-year term, which was later extended to a 25-year term, two years later.

The court found Fujimori guilty of corruption and abuse of power.

Announcing his decision, Kuczynski said, "I am convinced that those of us who consider ourselves democrats cannot allow Alberto Fujimori to die in prison. Justice is not vengeance. All pardons are by nature controversial. There is an important number of Peruvians who are opposed."

"My decision is especially complex and difficult, but it is my decision. I can not only be the president of those that voted for me, I need to be it for all Peruvians," he added.

Fujimori was moved to the hospital from prison, where he is undergoing treatment for low blood pressure and irregular heartbeat.