The Honduran army has ousted president Manuel Zelaya and exiled him in Central America's first military coup since the Cold War.
Honduran deputies named Congress head Roberto Micheletti as acting president to replace Mr Zelaya.
US President Barack Obama and the European Union have expressed deep concern after troops came for Mr Zelaya, an ally of Venezuelan President Hugo Chavez, around dawn (local time) and took him away from his residence.
Speaking on Venezuelan state television, Mr Chavez said he would do everything necessary to abort the coup against his close ally.
A military plane flew Mr Zelaya to Costa Rica and CNN's Spanish-language channel said he had asked for asylum there.
Pro-government protesters burned tires in front of the presidential palace in the Honduran capital, Tegucigalpa.
Honduras had been politically stable since the end of military rule in the early 1980s, but Mr Zelaya's push to change the constitution to allow him another term has split the country's institutions.
He fired military chief General Romeo Vasquez last week for refusing to help him run an unofficial referendum today on extending the four-year term limit on Honduran presidents.
The country's Supreme Court last week came out against Mr Zelaya and ordered him to reinstate fired General Vasquez.
The court said today it had told the army to remove the president.
‘It acted to defend the rule of law,’ the court said in a statement read on Honduran radio.
