The beginning of US President George W. Bush's five-nation Latin American tour sparked protests across the region on Thursday, with thousands of demonstrators and police clashing in Brazil and students in Colombia lobbing explosives at authorities.
More than 6,000 students, environmentalists and left-leaning Brazilians held a largely peaceful march through the heart of Sao Paulo before police fired tear gas at protesters and beat them with batons. Hundreds fled and ducked into businesses to avoid the chaos, some of them bloodied.
Authorities did not say how many people had been injured, but Brazilian media said at least 18 people were hurt and news photographs showed injured people being carried away.
Protesters said scuffles broke out when radical demonstrators provoked officers and threw rocks and sticks at them -- but said police overreacted. A police officer who declined to give his name in keeping with department policy confirmed that extremists appeared to cause the confrontations.
After the clash, the protest continued peacefully but with far fewer people. The marchers waved communist flags and railed against Bush, the war in Iraq and the ethanol proposal. Almost all had departed by sundown, and the streets were calm several hours later when Bush arrived in Sao Paulo.
In the southern Brazilian city of Porto Alegre, more than 500 people yelled "Get Out, Imperialist!" as they marched to a Citigroup Inc. bank branch and burned an effigy of Bush. Protesters also targeted the US Consulate in Rio de Janeiro, splattering it with bright red paint meant to signify blood.
In Colombia, about 200 masked students at Bogota's National University clashed with 300 anti-riot police carrying shields and helmets. The students were spray-painting anti-US slogans on walls and shouting "Out, Bush!"
Police fired water cannons and tear gas, and the students hurled back rocks, fireworks, a few Molotov cocktails and dozens of "potato bombs" -- small explosives made of gunpowder wrapped in foil. There were no immediate reports of injuries or arrests.
The Colombian demonstrators called for the scuttling of a US-Colombia free trade agreement signed in November and currently stalled in US Congress, and accused Washington of meddling in the South American nation's internal affairs by sending some US$700 million a year in mostly military aid.
Colombia is beefing up security in the capital for Bush's visit tomorrow, the first by a sitting US president since Ronald Reagan in 1982. About 21,000 security agents will patrol the capital.
Meanwhile, Colombia's police chief said authorities have foiled leftist rebel plans for terrorist acts to disrupt Bush's visit, but offered no details.
Asked about the protests, White House spokesman Gordon Johndroe said Bush "enjoys traveling to thriving democracies where freedom of speech and expression are the law of the land. He has a positive agenda here that we believe the people of Brazil and the rest of the Americas will benefit from."
Some protesters in Brazil carried stalks of sugarcane -- which is used to make ethanol -- and a banner reading: "For every liter of ethanol produced, 4 liters of fresh water are consumed, monoculture is destroying the nation's greatest asset."
"Bush and the United States go to war to control oil reserves, and now Bush and his pals are trying to control the production of ethanol in Brazil. And that has to be stopped," said Suzanne Pereira dos Santos of Brazil's Landless Workers Movement.