The country's supreme court sentenced a prominent opposition mayor in the middle of the night to 15 months in prison and stripped him of his right to hold political office.
Ramon Muchacho, the mayor of the upscale Caracas municipality of Chacao, was one of a group of opposition mayors who had been threatened with arrest for failing to prevent street protests in their jurisdictions.
Recent demonstrations in Venezuela have stemmed from anger over the installation of an all-powerful Constituent Assembly that many see as a power grab by the unpopular President Nicolas Maduro.
The dire economic situation also has stirred deep bitterness as people struggle with skyrocketing inflation and shortages of food and medicine.
In a statement after the ruling, Muchacho said he had been convicted for guaranteeing the right to peaceful protest and for "fighting for change in Venezuela."
Meanwhile, the Constituent Assembly -- packed with Maduro loyalists -- voted unanimously its backing for the military, following a weekend raid on an army base by rebels who officials said were "terrorists" supported by the United States.
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The raid on Sunday was apparently led by two renegade officers, one on active duty and the other who had been discharged three years earlier.
The military is still searching for them after they and other uniformed men fled with weapons stolen from the base's armory.
The country's defense minister and head of the armed forces, General Vladimir Padrino, addressed the Constituent Assembly in uniform.
Outside, police dispersed a small knot of protesters while pro-government militants prevented lawmakers from the rival, opposition-controlled parliament that shares the same Legislative Palace from entering.
Late Monday, the head of the pro-Maduro assembly, former foreign minister Delcy Rodriguez, led soldiers and others in invading the chamber where the opposition-controlled National Assembly meets, sharpening tensions between the rival bodies.
'Excessive force'
The UN rights office based in Switzerland lamented what it called "widespread and systematic use of excessive force and arbitrary detentions against demonstrators in Venezuela."
It highlighted witness accounts of police and soldiers using "disproportionate force to instill fear, crush dissent, and to prevent demonstrators from assembling, rallying and reaching public institutions to present petitions."
UN chief Antonio Guterres "is concerned that recent developments could lead to further escalation of tensions," his spokesman said in a statement.
Four months of street protests, accompanied by violent clashes with security forces, have left nearly 130 people dead.
Major Latin American nations have rejected the legitimacy of the Constituent Assembly, and South American nations have indefinitely suspended Venezuela from the Mercosur trading bloc for breaking "democratic order."
Foreign ministers of 16 Latin American and Caribbean nations as well as Canada met in Peru on Tuesday to evaluate further measures.
Colombian President Juan Manuel Santos has warned it "can't be excluded" that relations with Venezuela could be cut.
Peru was urging that Maduro's government be condemned for carrying out "a new form of coup d'etat" through the "unconstitutional" Constituent Assembly, that political prisoners in Venezuela be freed, and that the country hold scheduled elections, diplomatic sources said.
It also wants the group to condemn the new assembly's firing of Venezuela's attorney general, Luisa Ortega, an outspoken critic of Maduro, after she broke ranks with him.
The July 30 election of the Constituent Assembly was marred by street violence in which 10 people died, and charges of fraud brought by the British-based company that supplied the polling technology.
To counter the perception that it was isolated internationally, Venezuela on Tuesday hosted a meeting of allied nations in Caracas. It gathered foreign ministers and representatives from Cuba, Bolivia, Ecuador and Nicaragua, and a number of Caribbean nations that receive cheap Venezuelan oil.
Base raid
Sunday's raid on the army base in Valencia, the country's third largest city, heightened fears that Venezuela's crisis could tip into some form of armed conflict.
According to the government, two rebels were killed and eight captured.
The rest of the raiding party -- some 20 armed men in uniforms -- remained at large.
Padrino has assured that morale in the military is "very high."
Analysts said discord could be seen in the lower ranks of the security forces.
"There are indications of growing discontent in the middle ranks of the police and soldiers, even though military commanders remain allied to the government," said Diego Moya-Ocampos, of IHS Markit Country Risk in London.
"You can expect new incidents to occur as this unease grows," he said.
On Monday, hackers hijacked the home pages of several government bodies and private companies in support of the rebel raid, posting excerpts from Charlie Chaplin's movie "The Great Dictator."
