Venezuela's opposition leader Juan Guaido condemned a raid by military intelligence agents who searched his detained uncle's home on Thursday, and vowed he would not bow to government "repression."

His uncle, Juan Marquez, was arrested February 11 on his return to Venezuela with Guaido at the end of an international tour to drum up international support for his efforts to oust President Nicolas Maduro.

The government alleged Marquez was smuggling explosives into the country on the flight from Portugal, a claim strongly denied by Portuguese authorities.

Guaido denounced the search of his uncle's residence in Caracas by military counterintelligence agents on Twitter as it was happening, and said it was an attempt to intimidate him.

"If they think we are going to retreat from the path that we have taken and are going to take, they are mistaken. We will move forward," he said on Twitter.

AFP journalists witnessed officials of the General Directorate of Military Counterintelligence being admitted to the building's car park by hooded uniformed men.

Outside the residence, opposition lawmaker Delsa Solorzano denounced the search as "completely illegal."

A vehicle used by Venezuela's military counterintelligence agency, the DGCIM, outside the home of opposition leader Juan Guaido's uncle during a search on Thursday
A vehicle used by Venezuela's military counterintelligence agency, the DGCIM, outside the home of opposition leader Juan Guaido's uncle during a search on Thursday AFP / Federico Parra

A lawyer for Marquez, Joel Garcia, said he had been barred from entering the property while the search was taking place.

"I tried to enter and the DGCIM officials didn't let me in. When they don't allow a trusted lawyer to accompany them it's because they came to plant evidence," Garcia told reporters.

He said Marquez's wife and two children, aged 12 and five, were in the apartment.

"What is happening is an attack on Juan Guaido, to force him to negotiate, to break his will," Garcia said.

For over a year, Guaido has used his leadership of the National Assembly to challenge Maduro's legitimacy, and has won recognition from more than 50 countries as Venezuela's acting president.

He defied a travel ban to make a three week trip to Europe and the United States to rally support for a cause that has so far failed to budge Maduro from power.

The United States, Guaido's most powerful backer, has warned of consequences if the opposition leader is arrested. But that has not kept the government from moving against his allies and associates.

Washington condemned Marquez's arrest, saying he was being held on "preposterous charges."

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