"The embassy is surrounded by police and the military ... I foresee bigger acts of aggression and violence, that they could be capable of even invading the Brazilian embassy," Zelaya said in an interview with Venezuelan broadcaster Telesur.
"We know we are in danger," he told reporters. "We are ready to risk everything, to sacrifice."
But the de facto Honduran government allowed Red Cross and US embassy staff to send in supplies and denied it was planning a raid on the embassy.
Roberto Micheletti, the man who replaced Zelaya, said he had no intention of ordering his men to enter the embassy.
"We want them [Brazil] to understand that they should give him political asylum [in Brazil] or turn him over to Honduran authorities to be tried," he said.
"We will respect international and national law. If [Zelaya] wants to stay there for five or 10 years, we don't have any problem with him living there," he added.
Martha Lorena Alvarado, a senior government aide, said the interim government said it has "not considered, nor will there be, a raid on the embassy to capture Mr Manuel Zelaya".
Brazil, which has warned Tegucigalpa that any action against its mission "would not be tolerated", on Tuesday called for an urgent UN Security Council on the crisis and the US said it had received the formal request and would relay it to other members of the body.
Luiz Inacio Lula da Silva, the Brazilian president, urged the Honduran de facto government to negotiate a way out of the political crisis.
The military-backed Honduran government ordered a shutdown of the capital beginning on Monday afternoon, closed all international airports and set up roadblocks on highways leading into town to keep Zelaya supporters away.
|Police used tear gas and batons to disperse Zelaya supporters from the embassy [Reuters]
But loyalists ignored the decree and surrounded the embassy, dancing and cheering and using their mobile phones to light up the streets after electricity was cut off to the area around the embassy.
Riot police fired tear gas at demonstrators and chased them away on Tuesday and the interim government later extended a curfew to Wednesday morning, citing "national security".
About 50 people have been reported wounded in clashes so far.
Soldiers toppled Zelaya at gunpoint and sent him into exile in his pyjamas in a coup on June 28, following his attempt to call a constitutional referendum on presidential term limits.
Micheletti has repeatedly refused to allow Zelaya to return, insisting he would be arrested if he returned.
Oscar Arias, the Costa Rican president who unsuccessfully mediated in talks between Zelaya and the interim government in July, told Al Jazeera that he was working on a new round of talks.
"I think it is much more civilised if we re-start the negotiations… So I have invited both the foreign minister of the de facto government and the Zelaya people to re-initiate this dialogue in my country," he said.
But Micheletti has said he will not reopen negotiations and insists Brazil should hand over Zelaya to "pay for the crimes he committed", which according to the interim government are corruption and violating the constitution.
Zelaya's surprise return to Tegucigalpa comes as world leaders gather at the United Nations in New York, putting renewed international pressure on the interim government to let him return to power.
Economic sanctions have already been imposed by the US government and the EU, while Zelaya has called for negotiations with the leaders who forced him from power.
His return has overshadowed campaigning for the November 29 presidential vote that the interim government hopes will restore the country's international legitimacy.