Brazilian authorities have called an emergency meeting after three Amazon environmental activists were murdered.
Among steps being considered is co-ordinated action by the federal and state governments in key areas, Brazilian media reported.
On Friday, rural leader Adelino Ramos was shot dead in the state of Rondonia, just days after two campaigners were killed in Para state.
All three, who worked to stop illegal logging, had received death threats.
Mr Ramos, widely known as Dinho, was shot by a motorist as he sold vegetables in Rondonia's capital, Porto Velho.
The Catholic Church's Pastoral Land Commission (CPT) said Mr Ramos had denounced illegal loggers in the states of Acre, Amazonas and Rondonia, and called for a camp to be set up to house rural workers forced off their land.
Mr Ramos had survived a bloody dispute in 1995, when 300 or so police officers opened fire on a landless workers' camp near the town of Corumbiara, killing at least 10 people.
His murder followed the killing on 24 May of a husband and wife team, Joao Claudio Ribeiro da Silva and Maria do Espirito Santo, near the city of Maraba.
The couple's bodies were found inside a nature reserve, Praialta-Piranheira, where they had been working for the past 24 years.
According to family and friends, the pair had been subjected to numerous threats in the past two years for their environmental activism.
On Saturday, farmer Eremilton Pereira dos Santos was found shot dead in the same area as the couple.
However, police say there is no link between the murders.
Monday's meeting in Brasilia is set to bring together different departments to discuss the latest violence.
"It's a complicated picture in that region, which has high levels of deforestation, violence and murders. We are going to propose a co-ordinated action between the federal and state governments," Roberto Vizentin, Brazil's interim environment minister, told the Globo website.
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