At least five police officers have been injured and 10 protesters charged with assault. Despite unrest on the streets outside, however, the convention's second day went ahead as planned - with American military might the predominant theme. Delegates were told that the party's presidential candidate, George W Bush, would, if elected, push ahead with America's controversial missile defence programme - despite Russian opposition to the plan and the reluctance of US allies.
Protesters defiant Some delegates had trouble getting from their hotels to the convention centre.
The protesters linked arms at several intersections in central Philadelphia in an attempt to block traffic. A police spokeswoman told the BBC that three police officers had been injured when an unidentified liquid was squirted in their eyes. About 20 police cars and other vehicles were damaged. Protesters have been claiming victory, accusing police of inciting violence. Demonstrators have been trying to draw public attention to a range of issues including poverty, homelessness and the death penalty.