Police and soldiers have clashed with thousands of protestors demanding the reinstatement of Honduran President Manuel Zelaya, who was overthrown in a military coup over the weekend.
The centre-left president was arrested by armed troops who stormed his home before transporting him into forced exile in Costa Rica.
The move came just a day ahead of a vote designed to assess the public mood for a constitutional referendum that would allow Honduran presidents to serve more than one term.
At least 45 people were injured in today's clashes, including some who were hit by rubber bullets.
The US has condemned the coup and says it still regards Zelaya as the legitimate presidents.
Several Latin American countries have already responded by withdrawing their ambassadors from Honduras, while Venezuela has vowed to halt oil supplies to the country.
The Organisation of American States has also called an emergency meeting for today to consider suspending Honduras.