Nicaragua's leader Daniel Ortega said Wednesday that 19 opposition figures arrested just five months before a presidential election are not politicians but "criminals" who want to "overthrow the government."
In raids that began on June 2, security and paramilitary forces have arrested five opposition presidential challengers as well as journalists, businessmen and a banker.
Cristiana Chamorro -- daughter of former president Violeta Barrios de Chamorro and a favorite to face Ortega in November's poll -- was among those held.
"We are not dealing with pre-candidates, but criminals who have attacked the country," Ortega said in an official televised ceremony, while accusing the imprisoned of being "agents of the Yankee empire" who "conspire against Nicaragua to overthrow the government."
"That is what we are pursuing, that is what is being investigated and that is what will be punished in due course."
Those held face charges of "inciting foreign interference" under a new law initiated by Ortega's government and approved by the legislature in December purported to defend Nicaragua's sovereignty. The law has been widely criticized as a means of freezing out challengers and silencing opponents.
The recent arrests have increased international condemnation.
At a session of the UN's Human Rights Council in Geneva on Tuesday, 59 nations issued a statement saying they were "deeply concerned that recently enacted laws unduly restrict political participation, freedom of expression, peaceful assembly and association" in Nicaragua.
The Organization of American States' (OAS) human rights council on Wednesday denounced a "new phase of repression" in the country, and urged the body's judicial arm to protect four of the detained opposition politicians: Juan Sebastian Chamorro, Jose Adan Aguerri, Felix Maradiaga and Violeta Granera.
During the OAS session, the United States' representative Bradley Freden, quoting Secretary of State Antony Blinken, said it was time for Ortega's government "to change course" and "allow the Nicaraguan people to fully exercise their rights -- including their right to choose their leaders in free and fair elections."
On Thursday, the OAS's judicial body, the Inter-American Court of Human Rights, demanded Nicaragua immediately release the four aforementioned opposition politicians.
The Costa Rica-based court gave Nicaragua's government until July 8 to report on the "urgent measures adopted to comply with this decision."
Ortega has been accused of authoritarianism by the opposition and international community, following the brutal repression of demonstrations against his administration in April 2018, which left more than 300 dead and thousands of exiles, according to human rights organizations.
A firebrand Marxist in his younger days, Ortega and his Sandinistas toppled a corrupt autocratic regime to popular applause and seized control of the country in 1979.
He ruled until 1990, returned to power in 2007 and has won two successive reelections. His vice president is his wife, Rosario Murillo.
The 75-year-old is widely expected to run again in the November election, though he has not said so.