The Honduran authorities have imposed a round-the-clock curfew and shut down airports after the dramatic return of ousted President Manuel Zelaya.
Mr Zelaya has taken refuge in Brazil's embassy in Tegucigalpa. Many of his supporters later gathered outside.
He said he had crossed mountains and rivers to return to the capital, where he said he was seeking dialogue.
In a televised address, interim leader Roberto Micheletti demanded that Brazil hand over Mr Zelaya to stand trial.
Mr Micheletti said Brazil would be held responsible for any violence.
"A call to the government of Brazil: respect the judicial order against Mr Zelaya and turn him into Honduran authorities," he said.
"The eyes of the world are on Brazil and Honduras."
read more
