Legislators in Nicaragua have approved a constitutional amendment that will strengthen the power of longtime President Daniel Ortega, who has been accused of cracking down on critics and political challengers.

The reforms, which 79-year-old Ortega sent to Congress this week “as a matter of urgency”, were approved unanimously on Friday by 91 lawmakers.

The changes elevate Ortega’s wife and vice president, Rosario Murillo, to the post of “co-president”. They also increase the presidential term in the Central American nation from five to six years and extend the executive’s control over the media.

According to the Nicaraguan Constitution, reforms must be approved in a second legislative period, in this case in 2025, before they become effective.

Government critics said the amendments would legalise the “absolute power” Ortega and his wife already wield in the country.

Ortega had first served as president from 1985 to 1990, returning to power in 2007.

He secured a fourth consecutive term as president in 2021 after an election campaign that was marked by a months-long crackdown on dissent and the arrests of dozens of opposition figures, including several presidential hopefuls.

Rights groups and international observers slammed the vote as a “sham” and accused the Sandinista leader of stifling dissent.

“The reform not only reflects the paranoia and insecurity of the Sandinista dictatorship, but also codifies a system that has no exact precedent in Latin America, dangerously resembling the North Korean model,” wrote exiled opposition leader, Felix Maradiaga, in the online media outlet Divergentes.

“These modifications reflect a desperate attempt to shield the Ortega-Murillo family from any eventuality,” he added.

Ortega’s government has shut down more than 5,000 NGOs since mass protests broke out against his rule in 2018. About 300 people died in the unrest, according to the United Nations.

Meanwhile, thousands of Nicaraguans have fled into exile — often to neighbouring Costa Rica — and the United States and European Union have imposed a series of sanctions against Ortega’s administration.

“Nicaragua is being stripped of its intellectual capital and critical voices,” a UN panel warned last year.

Friday’s constitutional amendment stipulates that “traitors to the homeland” can be stripped of their citizenship – something Ortega has already done with hundreds of politicians, journalists, intellectuals and activists perceived as critical of his government.

It also gives the co-presidents the power to coordinate all “legislative, judicial, electoral, control and supervisory bodies, regional and municipal”.

The Organization of American States, a regional body, has slammed the reforms as “a definitive attack on the democratic rule of law”.

“Through these modifications to the fundamental law, Ortega and his allies seek to increase their absolute control of the State and perpetuate themselves in power,” the group said in a statement on Wednesday.