Former parliamentary speaker Roberto Micheletti, sworn in on Sunday as acting president by the Honduran Congress, swiftly imposed a 48-hour nationwide curfew starting on Sunday night, hours after a military coup which toppled President Manuel Zelaya pushed the Central American country into crisis.

“He transformed this coup into a completely legal act with daring tact,” said Laurence Cuvillier, FRANCE 24’s correspondent in Mexico. “He claims to have been named president by a legal process and in accordance with the law. He is referring to the Constitution, according to which the army – which captured and expelled Zelaya – implements orders of the Supreme Court.”

Ousted Honduran President Manuel Zelaya spoke to Latin America's Telesur TV just hours after his arrival in Costa Rica.

Meanwhile, several hundred Zelaya supporters ignored warnings to stay at home and took to the streets of Tegucigalpa, the capital, in support of the ousted president. A politically powerful union of teachers announced an indefinite strike to protest the coup.

Zelaya, who was seeking constitutional changes to extend his mandate beyond 2010, was bundled away in his pyjamas by the military early on Sunday and forcibly flown to Costa Rica.

The National Congress voted unanimously to remove Zelaya from office for his "apparent misconduct" and for "repeated violations of the Constitution and the law, and disregard of orders and judgments of the institutions.”

The ouster comes in the wake of disputes among Zelaya, the military and the judicial institutions over the president's bid to hold an unofficial referendum, which had been planned for Sunday. The Supreme Court said it ordered the removal to protect law and order in the country and that the armed forces "acted to defend the state of law".

Last week, the Zelaya tried to sack the the top military chief, General Romeo Vasquez, and accepted the resignation of Defence 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 handed in their resignations.

Extraordinary meeting in Nicaragua

The Honduran military coup is the first in Central America since the Cold War, and the situation has put regional leaders on high alert.

The Permanent Council of the Organization of American States (OAS) strongly condemned the military ouster and demanded the immediate and unconditional return of Zelaya.

Venezuelan President Hugo Chavez, a strong ally of Zelaya, convened an extraordinary meeting of the Bolivarian Alliance for the People of Our America (ALBA) in Managua, Nicaragua. The ousted Honduran leader also travelled to take part in the summit. Zelaya told reporters he was determined to return and "reclaim his post".

“It’s likely [the ALBA presidents] will come out tomorrow very strongly against the coup, and it will be interesting to see where it will go from there,” said Thom Walker, FRANCE 24 correspondent in Caracas, Venezuela.

Chavez said he had put his troops on alert after the coup and would do everything necessary to abort the ouster.

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

"After an initial condemnation from the United States, the European Union and other powers around the world, a lot of people thought the coup plotters would back down," Global Radio News Mexico correspondent Ioan Grillo reported for FRANCE 24. "But this shows they are not backing down. They are putting a new person in power; they are calling him legitimate."

The United Nations General Assembly is due to discuss the crisis on Monday.

Obama expresses "deep concern"

US President Barack Obama condemned the coup and called for calm. "Any existing tensions and disputes must be resolved peacefully through dialogue free from any outside interference," he said in a statement.

A senior Obama administration official later added that Washington recognised only Zelaya as president.

At the same time, Washington warned Chavez and his allies that the "process" in Honduras should not be "interfered with bilaterally by any country in the Americas".

A senior US State Department official said that Washington was working with other OAS members on a consensus resolution to condemn the effort to depose the president and call for full restoration of democratic order.