Guaido's envoy to Brazil, Maria Teresa Belandria, said in a statement on Wednesday that some embassy personnel communicated early on Wednesday that they "recognize President Juan Guaido" and were prepared to "voluntarily (hand over) the diplomatic headquarters to the legitimately accredited representation in Brazil", Efe news reported.
Guaido, the speaker of Venezuela's opposition-led but toothless National Assembly, refuses to accept Maduro as Venezuela's head of state and early this year proclaimed himself to be that nation's rightful president.
He is supported in his bid to take power by the United States, most European nations and Brazil, among other countries, although Maduro also has powerful backers led by China and Russia and most importantly has enjoyed the unwavering support of Venezuela's military.
Belandria arrived in Brazil in February, less than a month after Guaido was sworn in by the National Assembly as Venezuela's president.
She praised what she said was the embassy employees' "recognition of the legitimate government of President Guaido" and called on "all accredited officials at the embassy and in the seven Venezuela consulates" to take the same step.
But although Belandria said embassy officials had given their consent for Wednesday's development, the embassy's charge d'affaires, Freddy Meregotti, said that the diplomatic mission had been "invaded" and "remains under siege."
"I want all of you to be aware that we continue to unconditionally support the constitutional president of (Venezuela), who is Nicolas Maduro," Meregotti said in a video alongside Brazilian lawmaker Paulo Pimenta of the opposition Workers Party (PT).
Pimenta, for his part, said there had been "quite a violent confrontation" inside the embassy.
"There are signs that Brasilia's police or the Foreign Ministry itself facilitated and protected the actions of the coup plotters who tried to take that space by force," he added.
Brazil's government, however, said in a statement that rightist President Jair Bolsonaro "was never aware and much less encouraged the invasion of the Venezuelan embassy by supporters" of Guaido.
"The security forces, of the state and Federal District (Brasilia), are taking measures to ensure the situation is resolved peacefully and that normality is restored," the president's office said, lamenting that "unscrupulous individuals" want to "take advantage of the events to create disorder and instability."
Associates of Guaido inside the embassy in Brasilia told Efe that Military Police officers are at the scene and that the situation is tense but calm.
Sources from Brazil's Foreign Ministry also told Efe that at least two Brazilian diplomats had travelled to the embassy in an attempt to mediate among the parties.
The incident comes at an awkward time for Bolsonaro's government given that the leaders of the BRICS nations - Brazil, Russia, India, China and South Africa - began meeting Wednesday in Brasilia for a two-day summit.
Brazil is the only member of that association of emerging market countries that recognises Guaido as Venezuela's legitimate president.
( With inputs from IANS )