It has been an uneasy ride for Daniel Ortega and his Sandinista party since they re-took power in Nicaragua a little under two years ago. Criticism of his rule has accelerated at an almighty pace on everything from the economy to international relations.

Perhaps that's why concern is growing over the erosion of press freedom and civil rights in the Central American country - Ortega appears to be on a crusade to gag his opponents in the media and beyond. Those fears gathered apace this week after Reporters Without Borders condemned a campaign of vilification by the state media against prominent feminist and freelance journalist Sofía Montenegro.

The journalists' rights group said Montenegro was being exposed to danger by insults and defamatory remarks aimed at her. "Canal 4 television and Radio Ya have attacked the former militant with (Ortega's) ruling Sandinista National Liberation Front (FSLN) over her political stances, in particular in favour of decriminalising abortion," the group said. "Her detractors accuse her of being in the pay of the CIA'. She has also been accused of trying to block Nicaragua's regional integration into the Bolivian Alternative for the Americas (left-leaning regional alliance set up by Hugo Chavez, Venezuelan president). Accusations have also been made about her private life and her status as a journalist has been questioned."

It is just another in a string of alleged purges on sections of the media who dare question the Sandinista regime. Ortega's actions, in turn, have spawned cries of "Dictator".

Montenegro's case closely follows that of Jaime Arellano, a critical TV talk show host who saw the plug pulled on his programme by his bosses, who were believed to have come under pressure from the Ortega government. For his efforts, Arellano has been called "the fat devil". But it is the manner in which his show, 2 en la Nacion, was taken off the airwaves that worries government opponents and independent observers. Arellano, a former Conservative Party politician, claimed his bosses at Channel 2 ended his show because they feared reprisals from the Ortega government. In the lead-up to the switch-off, Sandinista supporters picketed the Channel 2 offices in protest at the show - an action repeated at opposition newspapers La Prensa and El Nuevo Diario.

The station's broadcast licence was up for renewal and had reportedly come under closer scrutiny. Arellano has a patchy recent history with Ortega. He was ejected from the Sandinista-affiliated Channel 10 for attacking the government. Since shifting to Channel 2, he had ratcheted his rants up a notch, regularly referring to Ortega's administration as a dictatorship and sending out a rallying call to the public to fight for democracy.

Arellano, who claimed he had also received death threats, says he is being persecuted and plans to take the case to the Inter-American Commission on Human Rights. But the government has hit back by accusing Arellano of inciting violent protest.

The Inter-American Press Association has intimated its deep concern at developments. Gonzalo Marroquín, chairman of the group's freedom of the press committee, said, "We cannot fail to express our concern because it is also true that the Nicaraguan government has consistently adopted coercive measures that work against the free practice of journalism."

Last month, the children of the president of the Nicaraguan Water and Sewage Company accused opposition newspaper La Prensa of defamation for a report that alleged their mother, Ruth Selma, allowed her two children to use company vehicles under her name. "The report was part of a series of stories meant to expose nepotism in the authority, in which La Prensa also reported that Selma's niece was hired thanks to Selma's appointment," reported the independent weekly newspaper The Nica Times. Selma is said to have denied all accusations.

Even Catholic religious leaders - it was the Catholic Church who connived with Ortega to help propel him to electoral success in exchange for a tough anti-abortion line - have indicated concern over an apparent barbed approach in its dealings with domestic criticism. Priest, poet and former minister in the 1980s Sandinista government Ernesto Cardenal was prosecuted in a court case that was initially dismissed in 2005. Critics say it was only revived because Cardenal had criticised Ortega during a recent speech in Paraguay.

One of the parties affected is the Sandinista Renovation Movement (MRS), a breakaway from Ortega's own FSLN party. Dora Maria Tellez, who fought alongside Ortega in the 1970s to overthrow the US-supported Somoza dictatorship, went on a highly-publicised hunger strike in protest at the decision. Last weekend, the tense relationship between the rival factions turned violent when FSLN supporters blocked off the northern city of Leon - armed with sticks, machetes and firing mortars - to stop a planned protest march by members of the opposition, including the MRS. Five people were injured.

The new US ambassador to Nicaragua is Robert Callahan, said to have once been the right-hand man to John Negroponte - the man considered one of the architects of the Contra conflict in Nicaragua that saw the Sandinistas fight a proxy war with Washington in the 1980s. Ortega lost his grip on power a few years later.