Tegucigalpa, Honduras ? Police and soldiers clashed with thousands of protesters outside Honduras’ national palace Monday, leaving at least 45 people injured, as world leaders from Barack Obama to Hugo Chavez demanded the return of a president ousted in a military coup.

President Manuel Zelaya said he would seek to return to his country Thursday and reclaim control of the government. He said he would accept an offer from the head of the Organization of American States to accompany him to Honduras.

Across Latin America, leftist leaders pulled their ambassadors from Honduras and Nicaraguan President Daniel Ortega said El Salvador, Nicaragua and Guatemala would cut trade with neighboring Honduras for at least 48 hours. Venezuelan President Hugo Chavez called for Hondurans to rise up against those who toppled his ally.

“We’re ready to support the rebellion of the Honduran people,” Chavez said. He later vowed to halt Venezuelan oil shipments to Honduras and called for its soldiers to rise up against “that tyrannical, puppet government.”

Protests outside the presidential palace grew from hundreds to thousands, and soldiers and police advanced behind riot shields, using tear gas to scatter the protesters. The demonstrators, many of them choking on the gas, hurled rocks and bottles as they retreated. At least 38 protesters were detained, according to human rights prosecutor Sandra Ponce.

Red Cross paramedic Cristian Vallejo said he had transported 10 protesters to hospitals, most of them with injuries from rubber bullets.

In Washington, Obama said the United States 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.

“It would be a terrible precedent if we start moving backwards into the era in which we are seeing military coups as a means of political transition rather than democratic elections,” he added. “The region has made enormous progress over the last 20 years in establishing democratic traditions. … We don’t want to go back to a dark past.”