By Arshad Mohammed

WASHINGTON (Reuters) - Ousted Honduran President Manuel Zelaya on Tuesday accepted a U.S.-backed effort by Costa Rican President Oscar Arias to mediate an end to the political crisis in Honduras and said talks with his rivals would begin on Thursday.

"Our first meeting is set for Thursday, in Costa Rica," Zelaya," Zelaya told Honduran radio, speaking from Washington after talks with U.S. Secretary of State Hillary Clinton, saying he would meet the "protagonists" of the June 28 coup that ousted him.

Clinton urged Zelaya, a leftist who was toppled in a coup sparked by his efforts to change presidential term limits, to negotiate rather than try to force his way back into the country.

Zelaya had tried to fly home on Sunday, but the interim government stopped his plane from landing. At least one person was killed when troops clashed with pro-Zelaya protesters who went to the airport in the capital, Tegucigalpa, to meet him.

The coup in the impoverished Central American coffee and textile exporter has been widely condemned abroad, and posed a diplomatic challenge for U.S. President Barack Obama.

The Organization of American States took the rare step to suspend Honduras on Saturday after Honduras' interim authorities defied its ultimatum to reinstate Zelaya. But the group has failed to find a solution to the crisis.

ARIAS ROLE

Clinton said all issues should now be settled in talks with Arias, who won the Nobel Peace Prize in 1987 for helping to end political violence in Central America and whom she said was ready to begin negotiations in Costa Rica immediately.

"I believe it is a better route for him to follow at this time than to attempt to return in the face of the implacable opposition of the de facto regime," Clinton told reporters, referring to Zelaya.

"So, instead of another confrontation that might result in a loss of life, let's try the dialogue process and see where that leads, and let the parties determine all the various issues as they should," she added.

While backing a restoration of "the democratic, constitutional order" in Honduras, Clinton did not explicitly call for Zelaya to return to power, saying this should be negotiated by the parties themselves.

OBAMA COMMENTS

Some analysts wondered whether the United States may be tempering its support for Zelaya, although Obama said he said he should return to power.

"America supports now the restoration of the democratically-elected president of Honduras, even though he has strongly opposed American policies," Obama said in a speech in Russia.

"We do so not because we agree with him. We do so because we respect the universal principle that people should choose their own leaders, whether they are leaders we agree with or not," he added.

The United States has repeatedly condemned the coup in Honduras, which has a population of 7 million and is the third poorest country in the Americas after Haiti and Nicaragua. The coup was the first in Central America since the Cold War.

Defying the international pressure, Roberto Micheletti, appointed president by Honduran lawmakers after the coup, has insisted Zelaya was legally removed.

But in a sign he was ready to pursue diplomatic solutions, Micheletti said his interim government had accepted Arias as a mediator.

"We've accepted him as the mediator, given the high profile that the president of Costa Rica has," Micheletti told local radio in Tegucigalpa. But he added: "We maintain our position that President Zelaya should not return. He committed crimes and he must pay for them."

Micheletti's interim government says the ouster was a constitutional transition carried out by the army and supported by the Supreme Court because Zelaya had illegally tried to organize a vote on changing presidential term limits.

Zelaya took power in 2006 and had been due to leave office in 2010. He had riled the country's traditional ruling elite with his leftward shift and growing alliance with Venezuela's socialist President Hugo Chavez.

(Additional reporting by Patrick Markey and Mica Rosenberg in Tegucigalpa, Frank Jack Daniel in Caracas, Matt Spetalnick in Moscow; writing by Arshad Mohammed; editing by Frances Kerry)