Rural violence in Brazil has increased since President Luiz Inacio Lula da Silva took office in January, says a new report from the country's Pastoral Land Commission (CPT).
Violence has been used to prevent poor families occupying land
Its figures for the first three months of 2003 suggest 13 people died in conflicts over land, compared to nine in the same period last year.
The report blames the new Workers' Party government - historic ally of the landless movement or MST - for failing to crack down on landowner militias and dragging its heels on land reform.
But the Brazilian authorities contest the commission's figures as "subjective", and say they have registered only six deaths.
The government said it looked at police reports using strict criteria to judge whether a death was related to conflict over land.
In two decades, the MST has grown to an estimated one million members and has appropriated about five million hectares (50,000 square kilometres) of land - an area half the size of the US state of Ohio.
It has historically eschewed negotiated settlements, preferring to target unproductive or abandoned land with mass land occupations by some of Brazil's thousands of poor families.
Before coming to power, the Workers' Party promised it would implement far-reaching land reforms to address the severe inequalities of land distribution in Brazil.
But the MST has previously complained that government moves to redistribute 200,000 hectares of land are not enough.
And the commission's figures suggest that land invasions - far from slowing to make way for government reforms - grew from 26 in the first trimester of 2002 to 46 in the same period this year.
On Thursday, the commission suggested it was "impatience" on the part of the MST that prompted the increased pace of occupations.
MST leader Joao Pedro Stedile reiterated on Thursday that his organisation would ignore new legislation outlawing land occupations, calling it "the government's problem".
"Ours is to organise the workers in the field," he said, according to Brazilian newspaper O Estado de Sao Paulo.
The occupations are the "consequence of the social contradiction", he said.
However, Mr Stedile did say the MST had ordered members not to occupy government buildings and struck a conciliatory note, saying the new government was "sympathetic".
The commission's study was issued on Thursday - the seventh anniversary of the massacre of 19 landless activists at Eldorado dos Carajas in northern Brazil at the hands of military police.
The anniversary was marked with nationwide demonstrations by thousands of landless workers.
Meanwhile, the Rural Democratic Union - which represents landowners - on Thursday complained the government was "folding its arms" and doing nothing to prevent land invasions.
Its head, Luiz Antonio Nabhan Garcia, warned that landowners would "respond within the law".