Activists carry a banner that reads Get

President Bush and first lady Laura Bush arrive Thursday at Guarulhos International Airport in Sao Paulo, Brazil.

Sao Paulo, Brazil ? As President Bush flew here aboard Air Force One on Thursday, thousands of protesters shouting “Out Bush!” marched down this city’s main drag, Avenida Paulista.

Hundreds of riot police flanked at least 6,000 protesters near the city financial center, and the scent of tear gas hovered along the march route. At least three protesters and a news photographer were reported hurt as baton-wielding police and protesters clashed, but there was no immediate word on their condition. Authorities later said that 16 police officers suffered minor injuries.

“We don’t want Bush here,” shouted Marcelo Prado, 19, echoing a common sentiment. “Tell him to go home!”

Bush arrived Thursday to begin a five-country Latin American visit designed to bolster U.S. standing in the region and counter the growing influence of Venezuelan President Hugo Chavez.

The trip is the president’s longest to date in Latin America, a region many Bush critics say has been largely ignored as the White House focused on Iraq and the Middle East.

In Brazil, Latin America’s largest and most populous nation, Bush and Brazilian President Luiz Inacio Lula da Silva are expected to unveil a new commercial partnership centering on ethanol, a plant-based gasoline substitute that Bush is championing as a future alternative to fossil fuels.

But in their pre-arrival protest, many here Thursday hoisted banners likening Bush to Adolf Hitler and warning Bush to keep his “hands off” Venezuela, while also decrying any U.S.-Brazilian bio-fuels pact as a plot by Washington to grab Brazilian resources.

“For Bush, this is a matter of getting cheaper fuel and getting out of the mess in the Middle East,” said Cristiana Coimbra, 35, a translator who wore a sticker featuring Bush with a swastika.

The protest march, which included representatives of environmental, student and labor groups, broke up before Bush’s plane touched down.

Brazilian police also were deployed in force to clear the route that Bush was scheduled to take from the airport to his hotel near downtown. Reports indicated that as many as 4,000 law enforcement officers were participating in one of the largest security operations in recent memory.

Anti-Bush rallies seem likely to follow Bush on his Latin America tour. On his last visit to the continent, in 2005, Bush never witnessed the massive demonstrations criticizing his presence at a hemispheric economic summit in Argentina.

Bush and first lady Laura Bush have planned a busy agenda for today, meeting with the Brazilian president and with a variety of community representatives.