MST members last week killed four guards from a ranch in the state of Pernambuco, northeast Brazil.
Brazil's Supreme Court, Minister Gilmar Mendes condemned the killings and accused the government of President Luiz Inácio Lula da Silva of promoting violence in rural areas by financing organizations linked to MST.
The heads of the Congressional Lower House Deputy Michele Temer and the president of the Upper House, Senator Jose Sarney as well as the country's National Agriculture Confederation supported the stance of the Federal Supreme Tribunal.
The group of benches representing rural interests in federal Congress said the MST was the Brazilian equivalent to the Colombian guerrillas FARC.
However Agrarian Development Minister Guilherme Cassel suggested that the president of the Supreme Court was involved in a "political statement" against MST.
"Illicit actions do not occur in abstract, we must find out which is the illegal contract of the government with MST, which was the illegal transfer of funds to be able to qualify and solve the situation", said Cassel.
The killing of the four guards at the Pernambuco ranch triggered a controversy over the MST which last January commemorated its 25th anniversary with a wave of rallies, marches, farm invasions in all the country and promises to continue the struggle for the agrarian reform.
The peasants' organization said over the weekend that the killing of the four "gunmen" was an act of self defense.
"It is common for policemen to act inside the armed militias in the camp and this has been the motive of several conflicts with landless peasants", added the MST release.
However the release did not explain why its members were carrying fire arms.
Mercopress