Brazil's former president Jair Bolsonaro has been permitted to leave prison to undergo surgery on Christmas Day following approval from Brazil's Supreme Court, court documents show.

Bolsonaro is currently serving a 27-year prison sentence for plotting a coup after he lost the last election in 2022.

Justice Alexandre de Moraes on Tuesday granted permission for Bolsonaro to temporarily leave prison and be transferred to a hospital on Wednesday for a hernia operation on 25 December.

Bolsonaro, 70, has faced ongoing health complications since being stabbed in the abdomen during a 2018 presidential campaign.

In April, the right-wing former president underwent intestinal surgery. By November, Justice Moraes, who also oversaw his trial, mandated that Bolsonaro be given full-time medical care. 

Flávio Bolsonaro, the former president's son, posted a video to X on Wednesday with the caption: "Keep praying for the president."

Bolsonaro was found guilty in September for plotting a coup d'etat after he lost the 2022 election to his left-wing rival, Luiz Inácio Lula da Silva.

The former leader is serving his sentence in a federal police jail in Brasilia, the capital, after being deemed a flight risk and removed from home detention.

Earlier this month, tens of thousands of people in Brazil's main cities gathered to protest against a billtrying to significantly reduce the time Bolsonaro spends in jail.

Lawmakers passed the bill last week after it was approved by the lower house. Legal experts have estimated it could reduce Bolsonaro's sentence to less than three years. 

In response, Brazil's president Lula promised to veto the bill.

"With all due respect to the Congress, when it reaches my desk, I will veto it," Lula told journalists last week, while acknowledging his veto could be overridden by the largely conservative Congress.

US President Donald Trump, who had previously called the investigation into Bolsonaro a "witch hunt", welcomed the bill being passed. The US also lifted sanctions that had been placed on Justice Moraes in July.