A dozen police suffered minor injuries Wednesday in a clash arising from a march here by thousands of members of Brazil's MST Landless Movement to protest what they call a "paralysis" of agrarian reform under President Dilma Rousseff.
The violent confrontation occurred outside the presidential palace when a group of MST activists knocked down a security fence and tried to make their way to the building.
The protesters were pushed back by police after brief clashes in which 12 officers sustained minor injuries.
Around 20,000 people, according to police, marched approximately 5 kilometers (3 miles) across Brasilia, pausing in front of the U.S. Embassy to denounce Washington's "imperial policy."
The demonstrators then headed to the Ministries Esplanade and passed by the presidential palace before ending their march outside the Congress building.
After the clashes, presidential chief of staff Gilberto Carvalho spoke with the protest leaders and acknowledged that the government's agrarian reform program was not unfolding "at the desired speed."
He offered to arrange a meeting between the MST leaders and Rousseff, possibly as early as Thursday.
The protest was organized as part of the MST's sixth National Congress.
During Monday's inauguration ceremony, the MST said the agrarian reform had ground to a halt because Rousseff, who took office in 2011, has "favored" the interests of rightist elements in her ostensibly center-left coalition.
"The agrarian reform plans are pushed back every year" amid resistance from "multinational corporations, banks, the media" and a governing coalition that has made a Rousseff a "hostage," MST official Diego Moreira said. EFE