Venezuela authorities have arrested two prominent critics of the government, a move rights groups say is a serious blow to freedom of expression in the country.
Guillermo Zuloaga, one of the heads of Globovision - a television news network that has been highly critical of Hugo Chavez, the president, was arrested on Thursday.
His arrest came a day after Oswaldo Alvarez Paz, a former opposition governor, was arrested for criticising the government on a television show aired earlier this month.
Paz was arrested on charges of conspiracy, criminal incitement and making false statements, for saying that Venezuela had become a drug-trafficking hub.
His arrest ahead of September's legislative elections was condemned by the opposition, who called it "unconstitutional" and "a brazen manipulation of justice [to] instil fear and self-censorship" among all Venezuelans.
Luisa Ortega, the attorney-general, said she issued an arrest warrant for Zuloaga, because he "was about to leave the country trying to get himself out of a criminal case".
Zuloaga confirmed by telephone to his Globovision network that police had detained him at the airport in the northeastern city of Punto Fijo, where he said he was planning to leave the country with his family on vacation.
He said that he had not been informed of any arrest warrant against him.
"This is another abuse," Zuloaga told Globovision. "I have no intention of leaving Venezuela now nor any time soon."
Earlier in the week, Venezuela's National Assembly asked Ortega to investigate recent statements Zuloaga made at a media conference in Aruba and to consider legal action.
According to the assembly, which is dominated by pro-Chavez legislators, Zuloaga lied about Venezuelan government activities, and was attempting to portray Chavez as a criminal to tarnish his reputation.
Chavez has accused Globovision of "media terrorism".
The network was in 2009 forced to pay a $4.1m fine for failing to acknowledge it aired ads favouring an opposition strike in 2002.
The network says government actions against it are politically motivated.
Zuloaga's arrest coincides with a damning report by the Inter American Commission on Human Rights denouncing Venezuela's persecution of political opponents, and accusing it of using the power of the state to attack its political enemies.
Public debate in Venezuela "is being increasingly reduced through the use of instruments such as the criminal justice system to silence critical or dissident expressions", said the commission, an independent rights body of the Washington-based Organisation of American States (OAS).
"It is extremely troubling that those who make allegations or state opinions about the situation in the country are charged with such offenses as the instigation to commit a crime."
Miguel Insulza Jose, the OAS secretary-general, called on Venezuela to "promptly free" Zuloaga.
"I worry about the national and international political repercussions of this situation," he said in a statement on Thursday.
The OAS chief also said that should Zuloaga be tried, it should be done "with respect for the presumption of innocence and with all the guarantees offered to him by the law".