TEGUCIGALPA, Honduras - Police fired tear gas to hold back thousands of Hondurans outside the occupied national palace Monday as world leaders from Barack Obama to Hugo Chavez appealed to Honduras to reverse a coup that ousted the president.

Roberto Micheletti, whom Congress appointed president on Sunday, vowed to resist the pressure and serve out the term of Manuel Zelaya, which expires in January. He insisted Zelaya was legally removed by the courts and Congress for violating Honduras' constitution, allegedly by trying to extend his rule.

Zelaya was arrested in his pyjamas by soldiers who stormed his residence and flew him into exile. Central America's first coup in at least 16 years was a blow from the barracks that reminded many of the military dictatorships the region has tried to bury in its past.

Obama said the United States still considers Zelaya the president of Honduras. He said the U.S. will "stand on the side of democracy" and work with other nations and international groups to resolve the matter peacefully.

"We believe that the coup was not legal and that President Zelaya remains the democratically elected president there," Obama said.

Zelaya attended a meeting in Nicaragua of a bloc of nine leftist nations, which agreed to remove their ambassadors from Honduras until Zelaya is restored and to reject diplomats from the replacement government.

Venezuelan President Hugo Chavez, one of the leaders in Nicaragua, urged Hondurans to rise up against the new leadership, saying: "We're ready to support the rebellion of the Honduran people." Chavez, who earlier vowed to "overthrow" Micheletti, did not say what kind of support Venezuela would provide.

Micheletti shrugged off the threat, telling HRN radio: "Nobody scares us."

Outside the presidential palace, a crowd that burned tires and blocked streets grew into the thousands by midday. At one point, riot police posted between troops and protesters fired several cannisters of tear gas and reporters saw at least five people detained. There were no reports of broader disturbances.

"We want our elected and democratic president, not this other one that the world doesn't recognize," said Marco Gallo, a 50-year-old retired teacher.

Most people in the capital went about business as normal. Nearly all businesses were open and traffic flowed normally aside from a small part of downtown Tegucigalpa.

Micheletti said he was sure that "80 to 90 per cent of the Honduran population is happy with what happened."

True or false, the rest of the world certainly was not, and the president of the U.N. General Assembly invited Zelaya to address the world gathering.

The Organization of American States called for Zelaya's return and summoned a meeting of foreign ministers on Tuesday that could make Honduras the first nation suspended from the organization under a 2001 charter banning "the unconstitutional interruption of democratic order." U.N. Secretary-General Ban Ki-moon and the Rio Group, which comprises 23 nations from the hemisphere, also condemned the coup and called for Zelaya's return.

U.S. diplomats said they are trying to ensure Zelaya's safety and get him restored as president. Secretary of State Hillary Rodham Clinton signalled, however, that the U.S. wasn't siding fully with Zelaya, who had rejected several Supreme Court decisions before being overthrown.

"There are certain concerns about orders by independent judicial officials that should be followed," Clinton said. "But the extraordinary step taken of arresting and expelling the president is our first and foremost concern right now."

She indicated the State Department has not formally declared Zelaya's ouster to be a coup because U.S. laws would then require cutting aid to the impoverished country.

Conservative Latin American governments also denounced the takeover. Mexico announced it was giving diplomatic protection to Zelaya's foreign minister, Patricia Rodas, who fled to Mexico City.

Zelaya was arrested and flown to Costa Rica hours before a rogue referendum he had called in defiance of Honduras' courts and Congress. His opponents claimed the vote was an attempt to remain in power after his term ends Jan. 27.

Micheletti said he would serve only until the end of Zelaya's term.

"We respect everybody and we ask only that they respect us and leave us in peace because the country is headed toward free and transparent general elections in November," Micheletti said.

His designated foreign minister, Enrique Ortez Colindres, told HRN that no coup had occurred. Ortez said the military had merely upheld the constitution "that the earlier government wanted to reform without any basis and in an illegal way."

The Honduran constitution limits presidents to a single four-year term and forbids any modification of that limit. Zelaya's opponents feared the referendum was part of an attempt to try to run again, just as other Latin American leaders have removed constitutional clauses designed to prevent strongmen from extending their rule.

The president of Latin America's largest nation, Brazil's Luiz Inacio Lula da Silva, said on his weekly radio program that his country will not recognize any Honduran government that doesn't have Zelaya as president "because he was directly elected by the vote, complying with the rules of democracy."

He also said Honduras risks isolation from the rest of the hemisphere.

"We in Latin America can no longer accept someone trying to resolve his problem through the means of a coup," Silva said.

Coups were common in Central America until the 1980s, but Sunday's ouster was the first military power grab in Latin America since a brief, failed 2002 coup against Chavez.

It was the first military ouster of a Central American president since 1993, when Guatemalan military officials refused to accept President Jorge Serrano's attempt to seize absolute power and removed him.