A federal judge has suspended a planned hearing for fishermen and indigenous people occupying a disputed dam in Brazil's Amazon after they failed to vacate the site, developers said.

Federal Judge Marcelo Honorato had summoned for a hearing on Monday representatives of both the Norte Energia consortium in charge of the Belo Monte Dam and of the dozens of fishermen and natives occupying the dam's Pimental construction site for a week.

He had warned that the meeting would occur only if the activists end their occupation of Pimental, one of the dam's five construction sites. The protesters had until Saturday morning to vacate the premises.

"The conciliation hearing has been suspended because the occupiers have not vacated the Pimental work site," Norte Energia said on its website.

"An officer of the court overflew the occupied area and found that the protesters were still there."

Court officials were not immediately available to confirm the claim.

Protesters accuse Norte Energia of backtracking on accords signed in June when 150 indigenous people occupied the Pimental area for three weeks.

The natives want their lands demarcated and non-indigenous people removed from them, as well as a better healthcare system and access to drinking water.

Indigenous groups fear the dam across the Xingu River, a tributary of the Amazon, will harm their way of life while environmentalists have warned of deforestation, greenhouse gas emissions and irreparable damage to the ecosystem.

Expected to produce 11,000 megawatts of electricity, the dam would be the third biggest in the world, after China's Three Gorges facility and Brazil's Itaipu Dam in the south.

It is one of several hydroelectric projects billed by Brazil as providing clean energy for a fast-growing economy.

The dam is, however, expected to flood an area of 500 square kilometers (200 square miles) along the Xingu and displace 16,000 people, according to the government, although some NGOs put the number at 40,000 displaced.

The federal government plans to invest a total of $1.2 billion to assist the displaced by the time the dam is completed in 2019.