Protests were held against the jailing of MST members
The Brazilian Government says it will punish those members of the Landless Peasant Movement (Movimento dos Trabalhadores Rurais Sem Terra) or MST, who have been taking part in land occupations.
Officials say the protesters will be excluded from receiving benefits under the agrarian reform programme.
The announcement came after protesters occupied a farm belonging to the family of President Fernando Henrique Cardoso last weekend.
The landless movement, is threatening to occupy land across Brazil in the coming months to demand land reform.
But the government says it has already carried out the largest land reform in contemporary history.
Threats
Agrarian Development Minister Raul Jungmann said that in his eight years in office, the government had given out more than 20m hectares.
But these figures are hotly disputed by the MST, who say far less land has been given out.
Over the past 10 years, land disputes have led to endemic violence in the countryside, with several hundred landless protesters being killed.
Mr Jungmann said that 16 MST leaders arrested at the weekend for leading an occupation of President Cardoso's family farm were all recipients of land under the government's programme, but they had now been excluded.
The 16 are still in jail despite an earlier promise from the government's agrarian ombudsman that there would be no arrests if they left the farm peacefully.
The ombudsman has since resigned, saying his word was broken.