The leader of Venezuela's National Assembly, Diosdado Cabello, on Monday accused the United States of kidnapping two nephews of first lady Cilia Flores.
The two were arrested in Haiti last week and taken by the US Drug Enforcement Administration to New York and charged with drug trafficking.
Mr Cabello said the arrests were "irregular" and had been carried out to damage the governing party ahead of legislative elections on 6 December.
US-Venezuelan ties have been fraught.
The two nations have not exchanged ambassadors since 2012 and Venezuela regularly accuses the US of trying to destabilise the Latin American country.
Mr Cabello, a powerful figure in the governing United Socialist Party (PSUV), was the first official to speak out about the arrest of the two men last Tuesday.
In an interview with Venezuelan TV, he said that he did not consider it an arrest.
"A plane went to Haiti with six people and they kidnapped two," he said referring to the fact that the four other people on board had not been charged.
"It's the DEA's normal procedure to kidnap lots of people," he alleged.
The aim of the arrests, he added, was "to hurt the Bolivarian revolution" in the midst of an election.
Some polls suggest that the governing coalition could lose its majority in the National Assembly for the first time in 16 years on 6 December.
Efrain Antonio Campo Flores, 29, and Franqui Flores de Freitas, 30, were charged with one count of drug trafficking on Thursday.
The two are nephews of first lady Cilia Flores and travelled on diplomatic passports.
Mr Cabello said they had acted independently: "These are grown men who can do what they want in life."
Their indictment accuses the men of conspiring to import "five kilograms [11 lb] and more of mixtures and substances containing a detectable amount of cocaine" to the US.
But Reuters said a US law enforcement source had told the news agency that the two men had allegedly planned to smuggle a much larger amount, 800kg, to the US.
Lawyers for the two men said they would plead not guilty at their next court appearance.