By Gary Duffy
BBC News, Sao Paulo
Brazil's disappearing rainforests have long been of concern
Brazilian President Luiz Inacio Lula da Silva is due this week to make one of the most keenly awaited decisions about land ownership in the Amazon rainforest.
The president has to decide by 25 June whether to veto parts of a bill that is due to transfer an area of public land - estimated to be around 670,000 square kilometres (259,000 square miles) - into private hands.
The government originally introduced what is called "Provisional Measure 458" as a way of bringing security to small farm owners in the Amazon region.
But critics say the proposal amounts to an amnesty for land-grabbers, and that the original measure has been altered by Congress in a way that will only serve to encourage deforestation.
Uncertainty over land ownership has long been a cause of violent conflict in the Amazon region, and presented an enormous obstacle for the authorities in their efforts to prevent illegal deforestation.
It was in order to tackle this issue the government introduced the proposal to transfer a vast area of land, roughly the size of France, into private hands.
The so-called "provisional measure" was meant to settle the question of ownership of hundreds of thousands of properties where those who occupied the land before 2004 had never been formally granted legal title.
The smallest areas, of less than 100 hectares (247 acres), would be handed over for free; medium-sized territory would be sold for a symbolic value, while larger estates of up to 1,500 hectares (3,707 acres) would be auctioned at market prices, but with 20 years allowed to make a repayment.
However, changes to the law mean the largest areas could then be sold on after a period of three years instead of 10, and critics fear this will lead to further exploitation of the rainforest.
Environmental groups have also complained that the law may allow lands to be registered by companies or by frontmen acting on behalf of large landowners.
Greenpeace says it was expecting the decision last week, but the fact that it did not come is a sign of division within government, and an indication of the huge pressure on President Lula, who it says is receiving thousands of phonecalls and e-mails on the issue.
"We know that within his government there is a lot of tension between the ministries of agriculture and environment, land reform and strategic studies," Marcelo Furtado, executive director of Greenpeace in Brazil, told the BBC News website.
"If he did not decide on any of the vetoes last week, our reading is that it is a bad indication that eventually the big landowners are actually having an impact on his approach."
"We are extremely concerned."
Mr Furtado says the bill, as it was originally presented, was already deeply flawed "in terms of the areas that would be privatised, in terms of who would have access to the land, in terms of lack of verification from any government authority on the status of the land".
"The problem is what we are finding in the Amazon is either the attitude of 'I am not going do anything because I am sure we will win this fight and change the law and make all the deforestation I have legal'," he said.
"Or the other attitude is that because there is so little governance here, because the government is so absent the truth is that we can just keep cutting down the forest and nothing will happen to us."
"This bill will be a major signal indicating to the people who enjoy impunity that it is worth committing a crime in the Amazon."
Not surprisingly, supporters of the measure dispute this assessment, and point as well to other initiatives that are under way in the Amazon.
The Amazon rainforest
Largest continuous tropical forest
Shared by nine countries
65% Brazilian territory
Covers 6.6m sq km in total
Pop: 30m - 23.5m are in Brazil
On Friday, the Brazilian government announced its so-called "Green Arch" proposal in which it will pay small farmers up to $51 (£31) per month to reforest degraded lands in 43 municipal areas where deforestation is a major issue.
The government has also set a target to reduce deforestation by some 70% by 2018, and says the indications from recent months are that it will be at its lowest level in two decades, due in part to an increase in policing measures.
President Lula says non-governmental organisations are "not telling the truth" when they say that the provisional measure will encourage land grabbers.
"What we exactly want to do is to guarantee that people have ownership of land, to see if we can end the violence in this country," he said last week.
"This is what we want to do, and this is what we are going to do," the president insisted.
There is a consensus that the issue of land ownership badly needs to be sorted out in the Amazon - but it seems this bill has not built on that common ground.
The heated debate over the measure has once again highlighted the divide in Brazilian society between a strong agricultural lobby keen to promote development, and environmental groups who fear for the future of the Amazon.
Whatever decision President Lula takes, it is unlikely to be free from controversy.