Honduras' Congress on Sunday appointed speaker Roberto Micheletti to replace ousted Manuel Zelaya as the country's acting president.

The announcement was made at a parliament session that began with the reading of a resignation letter that Zelaya said was false.

Honduras' congressional leader Roberto Micheletti, third left, is sworn in as the country's new President at the National Congress in Tegucigalpa, Sunday, June 28, 2009. [Xinhua]

The letter, read out by secretary of the legislature, Jose Alfredo Saavedra, said that Zelaya had resigned due to "serious health problems."

But later in the day, speaking at a joint press conference with Costa Rican President Oscar Arias Sanchez in San Jose, Zelaya said "I have not resigned."

Zelaya said he was kidnapped and flown to Costa Rica against his will and he did not sign a letter of resignation.

"I was kidnapped with force, violence and brutality," he said. Zelaya said that between eight and 10 hooded and heavily armed soldiers had entered his home and forced him to board a plane without telling him the destination.

"I was in my pajamas and did not even have socks on," he said.

"This move is a blow to a nation and a slap in the face for the whole world," he added.

Honduras' Supreme Court issued a statement backing the armed forces, saying that the coup was "actions taken based on rule of law."

Honduras was due to hold a national referendum on Sunday aimed to clear the way for Zelaya's re-election.

Zelaya, who was elected in November 2005 to a non-renewable four-year term, was set to step down in January, 2010.