Protesters in Guatemala say they will intensify their demonstrations against a trade deal with the US unless their demands are met on Wednesday.
The protesters fear the deal will harm small farmers and businesses
Tensions have risen since a protester was killed in clashes with police on Tuesday, the sixth day of unrest.
The protesters want a referendum on the Central American Free Trade Agreement (Cafta), as well as the resignation of the interior minister and police chief.
Cafta has sparked protests in several countries in central America.
It has yet to be ratified by the US, Costa Rica, Nicaragua and the Dominican Republic.
In Guatemala, the demonstrators - among them indigenous farmers, trade unions and students - say the deal will harm farmers and small businesses.
The government says it is essential for development.
Despite continuing talks sponsored by the Catholic Church, Guatemala's President Oscar Berger signed the law into effect on Tuesday.
On Monday, some 4,000 people demonstrated in the capital, Guatemala City.
Police used tear gas and water cannons to dispel the marchers, some of whom were throwing rocks and bottles.