TEGUCIGALPA: Honduras interim leader Roberto Micheletti imposed a nationwide 48-hour curfew after the army ousted elected President Manuel Zelaya and sent him into exile.

Congress voted Micheletti in as the country's new leader just hours after Zelaya fled, while insisting he was still president. Shots were heard in the Honduras capital late Sunday and the United Nations General Assembly was to discuss the crisis in the Central American nation on Monday.

Zelaya traveled to Costa Rica and later Managua to take part in a summit of radical Latin American leaders. He told reporters he was determined to return and "reclaim his post."

Venezuelan President Hugo Chavez, also in the Nicaraguan capital, vowed to do "everything that is necessary in political, diplomatic, social and moral aspects to restore the government of Manuel Zelaya."

In Honduras however, Micheletti brushed off worldwide condemnation of the takeover.

He "had came to the presidency not by a coup d'etat but by a completely legal process as set out in our laws," he said. The curfew would end on Tuesday, he added.

Micheletti issued a direct warning to Chavez, saying Honduras is determined to "go to war" if case of external interference on the part of "this gentleman."

The interim leader said he had information that several batallions of troops were being prepared outside of Honduras for intervention.

"I would not want anybody to have the courage to do that because our armed forces are ready to defend the country," he argued.

In the Honduran capital, shots were heard near the presidential palace late Sunday, but their cause was not immediately clear.

And a politically powerful union of teachers announced an indefinite strike to protest Zelaya's ouster.

As planes and helicopters overflew the capital, several hundred Zelaya supporters ignored warnings to stay home and took to the streets of Tegucigalpa shouting out, "We want Mel," the president's nickname.

The demonstration was halted in front of the presidential palace by a cordon of troops and armored vehicles.

Zelaya's overthrow was triggered by a standoff between the president and the military and legal institutions over his bid to secure a second term.

Congress said it had voted unanimously to remove the president from office for "apparent misconduct" and "repeated violations of the constitution and the law and disregard of orders and judgments of the institutions."

Micheletti was appointed to serve out the rest of the term, which ends in January. New general elections are planned for November 29.

Zelaya, elected to a non-renewable four-year term in 2005, had planned a vote Sunday asking Hondurans to sanction a referendum to allow him to stand again in the November polls.

The referendum had been ruled illegal by Honduras's top court and was opposed by the military, but Zelaya vowed to go ahead.

The Supreme Court said Sunday that it had ordered the president's ouster to protect law and order in the nation of some seven million people.

At dawn on Sunday, some 200 troops swooped on Zelaya's home. He was bundled away in his pyjamas and flown out of the country.

A leading government official, Armando Sarmiento, told AFP that at least eight cabinet members had also been detained including Foreign Minister Patricia Rodas.

US President Barack Obama said he was deeply concerned about the events in Honduras. US officials said they recognized Zelaya as the legitimate president.

But in a veiled warning to Chavez and his allies, a senior US State Department official said that "a process" in Honduras should not be "interfered with bilaterally by any country in the Americas."

Washington was working with other members of the Organization of American States (OAS) on a consensus resolution to condemn the effort to depose the president and call for full restoration of democratic order, he said.

Last week Zelaya sacked military chief, General Romeo Vasquez and accepted the resignation of Defense Minister Edmundo Orellana, after military commanders refused to distribute ballot boxes for Sunday's vote.

The heads of the army, marines and air force also resigned.

The Honduran Supreme Court unanimously voted Thursday to reinstate Vasquez and hundreds of troops massed late last week in the capital Tegucigalpa.

Zelaya, who was elected as a conservative, has shifted dramatically to the left during his presidency.