Hundreds of Peruvians on Sunday came out on the streets of Lima to protest against the pardon granted by the president to jailed ex-president Alberto Fujimori, who was serving a 25-year prison term for human rights abuses.

The protesters, including family members of the victims whose killings led to Fujimori's conviction, gathered in the central San Martin plaza, denouncing the pardon granted by President Pedro Pablo Kuczynski as an act of impunity.

Relatives of the murdered and disappeared people said that they will appeal to international bodies to cancel the pardon so that Fujimori, 79, completes his full sentence.

The protesters were carrying placards with messages criticizing Kuczynski and his decision to pardon the ex-president.

They said that the presidential pardon was illegal and the result of a political pact between Fujimori's supporters and Kuczynski to allow the latter to hold on to the post of president.

The agitators defied a large police deployment and minor scuffles broke out as they tried to move towards the Government Palace.

Kuczynski signed the pardon just three days after he was saved from an impeachment vote in the Congress by the support of around a dozen rebel lawmakers from the opposition, led by Kenji Fujimori, the ex-president's son who had called for his father's release on many earlier occasions.

Fujimori's supporters also gathered in fewer numbers outside the hospital where he is admitted, to celebrate the pardon.

The ex-president's children were cheered on by the supporters when they visited the leader, who is set to remain in the hospital at least until Monday.

The pardon was granted on humanitarian grounds, supposedly because Fujimori is suffering from a "progressive, degenerative and incurable disease" and is at risk of aggravation due to prison conditions, according to a statement from the Presidency of Peru.

Former president Fujimori (1990-2000) was sentenced in 2009 to 25 years in prison for his responsibility in the massacres of 25 people in 1991 and 1992, perpetrated by the undercover military group Colina, and the kidnapping of a journalist and a businessman in 1992.