Thousands of Peruvians took to the streets on Monday to protest against the pardon granted to the former president Alberto Fujimori, with many calling it part of a backroom deal struck to protect the current president from impeachment on corruption charges.

The Sunday pardon came three days after abstentions by lawmakers from a party led by Fujimori’s children caused the failure of a vote to impeach the president, Pedro Pablo Kuczynski. Fujimori, 79, was serving a 25-year sentence over the deaths of 25 people in a campaign against the leftist Shining Path terrorist group.

Roughly 5,000 people protested across the country carrying posters with Fujimori’s face and the words “murderer” and “thief”.

Fujimori, president from 1990 to 2000, is remembered for stabilising the economy and defeating the Shining Path, and for human rights violations and corruption.

In a message to the nation late on Monday, Kuczynski called for an “effort at reconciliation”, urging the protesters to “turn the page” and not be carried away by hate and “the negative emotions inherited from our past”.

Meanwhile Fujimori sought forgiveness from Peruvians “from the bottom of my heart” on Tuesday for shortcomings during his rule, and thanked Kuczynski for granting him a Christmas pardon.

In a video on Facebook, Fujimori vowed that as a free man, he would support Kuczynski’s call for reconciliation, hinting that he would not return to politics.

“I’m aware the results of my government were well received by some, but I acknowledge I also disappointed other compatriots,” he said, reading from notes while connected to tubes in a hospital bed. “And to them, I ask for forgiveness from the bottom of my heart.”

The remarks were Fujimori’s first explicit apology to the Andean nation that he governed with an iron fist from 1990-2000.

He was moved to a clinic on Saturday for what his doctors said was heart arrhythmia. His supporters said he would remain there until he was healthy enough to leave.

Kuczynski was accused of lying about his financial ties to the Brazilian construction giant Odebrecht, which paid hundreds of millions in bribes to public officials across Latin America in order to win lucrative public works contracts. Fujimori’s powerful lawmaker daughter, Keiko Fujimori, led the impeachment drive in Congress but legislators loyal to the ex-president’s son Kenji, also a lawmaker, killed the effort by abstaining.

Kenji Fujimori has long pushed for his father’s release from prison and Kuczynski’s opponents said the pardon was clearly payback for the abstentions that ended the impeachment drive. With Kuczynski under criminal investigation for his Odebrecht ties and weighed down by an 18% approval rating, observers said his long-term political survival still appeared to be in jeopardy.

“The pardon opens a Pandora’s box – the haste with which it was taken makes Kuczynski even more vulnerable,” said Jose Carlos Requena, an analyst with the political consulting firm 50+1.

Kuczynski’s business, Westfield Capital, received $782,000 from Odebrecht more than a decade ago. Kuczynski had denied any ties to the company until the evidence was made public this year. He later said that none of the contracts in question contained his signature and he had no knowledge of the payments.