(CNN) -- Venezuelan authorities arrested an opposition politician and former presidential candidate on explosives charges Monday night, the government news agency reported.
Alejandro Pena Esclusa, a 1998 presidential candidate and political opponent of leftist Venezuelan leader Hugo Chavez, was arrested at home by agents from the nation's intelligence service, the official ABN news service reported Monday. Pena was taken to the intelligence service headquarters for interrogation, ABN said.
Opposition groups say Pena was arrested for political reasons. Unoamerica, a group headed by Pena, said Tuesday his arrest "is part of a Cuban operation that looks to link opposition leaders with terrorist acts."
Chavez critics have said Cubans are heavily involved in the Venezuelan military and also are playing a key role in intelligence, communications and other areas.
Authorities say they found material of "an explosive nature" when they searched Pena's home in Caracas, Venezuela.
"We have obtained ... some small capsules, more than 100 capsules, which are presumed detonators, some thermal, some electric," ABN quoted counterintelligence director David Colmenares as saying.
Officials contend Pena has been working with Francisco Chavez Abarca, a Salvadoran resident arrested in Venezuela last week on charges that he was in the country to destabilize the government. ABN calls Chavez Abarca a "terrorist" and says he informed on some of his accomplices.
Pena is one of those accomplices, ABN indicated.
"Alejandro Pena Esclusa is a dark character of the Venezuelan opposition linked to fascist sectors and with a thick file of conspiratorial activities against the government of President Hugo Chavez," ABN said.
There will be other arrests in coming days as a result of the information Chavez Abarca provided, the news agency said.
Pena's strong opposition to the Venezuelan president has been lauded, even in the United States. The Alabama state legislature took up a resolution in March commending his actions.
"[A]t great personal risk to himself, Alejandro Pena Esclusa has stood firm in opposition to the spread of Marxism and totalitarianism in Latin America," the resolution states, adding that Pena "continues to serve as an ideological and symbolic counterweight to Chavez's grievance driven exploitation of the people of Venezuela and of broader Latin America in furtherance of the fomentation of authoritarian movements in the region."
Human rights organizations have frequently accused Chavez of intimidating or punishing citizens based on their political beliefs.
In June, the Inter-American Commission on Human Rights sent a letter to Venezuela's foreign minister, criticizing the government on its record of freedom of expression.
In February, the commission issued a 319-page report accusing Venezuela of routinely violating human rights. The report said that a lack of independence by Venezuela's judiciary and legislature in their dealings with Chavez often leads to the abuses.
"The report finds that not all individuals are ensured full enjoyment of their rights irrespective of their positions on government policies," the human rights panel said. "The commission also finds that the punitive power of the state is being used to intimidate or punish people on account of their political opinions."
The Inter-American Commission on Human Rights is an independent arm of the Organization of American States.
Chavez's opponents say his government represses political opponents and the expression of free ideas by jailing critics on trumped-up charges or pulling licenses for TV and radio stations and shutting down newspapers. There are about 40 such political prisoners in Venezuelan jails, the critics say.
Most of those prisoners, Chavez critics say, are journalists and former military and police officials and others associated with a short-lived coup against Chavez in April 2002.
Some of the prisoners have been held for long periods without trials or during proceedings that have dragged on for months and even years, the critics say, and they say other prisoners have received harsh sentences under questionable charges. Many of the detainees are held at the secret police headquarters rather than a prison.
"Attacks on journalists were widespread," said Amnesty International's 2009 Report on Human Rights in Venezuela. "Human rights defenders continued to suffer harassment. Prison conditions provoked hunger strikes in facilities across the country."
Human Rights Watch, an independent global organization, issued a 230-page report in 2008 that said Chavez has shown an "open disregard for the principle of separation of powers ... specifically, the notion that an independent judiciary is indispensable for protecting fundamental rights."
The Chavez government has routinely denied any allegations of human rights abuses, saying that authorities arrest citizens only on suspicion of breaking the law.