Around 20 protesters were reported killed last night after Bolivia's government sent thousands of troops backed by tanks to quell violent protests against President Gonzalo Sanchez de Lozada.
The protesters were killed during battles with troops clearing roadblocks that are choking food and fuel supplies to the capital in and around the poor industrial suburb of El Alto, outside La Paz, human rights officials said.
The government, which has played down death tolls in recent protests, said four civilians and one soldier were killed and that around 30 others were injured.
Yesterday's clashes raise the toll to around 30 dead and dozens injured during a month-long wave of protests against Mr Sanchez de Lozada's free-market policies and failure to tackle poverty in South America's poorest nation.
"It is difficult to come up with an exact toll, but according to the reports we have studied, there are 20 dead and 91 injured in or near El Alto," said Mr Waldo Albarracin, president of Bolivia's Permanent Human Rights Assembly.
Fuel and basic foods were running short in the capital as thousands of poor Bolivian farmers and workers calling for Mr Sanchez de Lozada to quit stopped convoys of trucks entering the Andean city with roadblocks.
A presidential spokesman said the government could order a curfew in El Alto at any time to stop what it perceived as a coup attempt by its opponents - a charge it has made on several occasions in the past.
Bolivia's flagship airline suspended flights out of La Paz due to security fears, but the international airport was still operating under the guard of troops.
The violence is the worst since February, when a government austerity drive backed by the International Monetary Fund sparked riots in which 32 people died.