Agents from Venezuela's Sebin intelligence service on Tuesday raided the offices of opposition leader Juan Guaido while he traveled in Europe, an opposition lawmaker said.
"We have just confirmed that Sebin officers are inside the office of president Guaido," lawmaker Delsa Solorzano told reporters after speaking with security guards at Caracas's Zurich Tower.
National Assembly leader Guaido has been recognized as president by the United States and more than 50 other countries in his year-long power struggle with socialist President Nicolas Maduro.
The tower where the offices are located had been surrounded in the afternoon by hooded and armed Sebin officers dressed in black.
The offices were empty when the search began, the opposition said, adding that several lawmakers had been unable to gain access.
"Whatever procedure is under way, they are carrying it out without authorization... without witnesses, and they have no search warrant," Solorzano said outside the building.
Lawmaker Angel Torres said the agents "abruptly entered" the offices, amid opposition fears they could plant false evidence.
The opposition had already reported earlier in the day the arrest of one of its members while he was headed to the Assembly. They named him as Ismael Leon.
Venezuelan authorities made no comment on that report.
The 36-year-old Guaido has defied a travel ban to fly to London for talks with Prime Minister Boris Johnson as part of a European trip which will include a visit to the World Economic Forum in Davos, Switzerland.
On Monday he visited Bogota, Colombia and met with US Secretary of State Mike Pompeo, who promised Guaido more US support in his effort to unseat Maduro.
Despite international backing, efforts to oust Maduro have stalled and he retains the support of the powerful armed forces, as well as that of allies China, Russia and Cuba.
The tower where the offices of Venezuelan opposition leader Juan Guaido are located was surrounded by hooded and armed Sebin intelligence officers dressed in black