Peru's main indigenous group said on Wednesday it will ask the courts to halt an expansion of the country's largest natural gas field over concerns that new drilling will harm isolated tribes.
Aidesep (the National Association of Amazon Indians in Peru), wants to overturn the regulatory approval issued in April for a $70-million project by the Camisea gas consortium in an oil block that overlaps an indigenous reserve.
It also wants to prevent other expansion plans in the reserve.
The filings, expected next month, could further delay President Ollanta Humala's ambitious energy agenda and build on a September ruling from Peru's constitutional court that upheld the right of indigenous communities to defend their lands from encroaching loggers or miners.
"It's not a binding precedent, but it was a hopeful sentence for indigenous people and we think we can do something similar," said Aidesep lawyer Julio Ibanez. "We have the law on our side and can win. We are tired of pressing our concerns with the government without getting results."
Argentine energy firm Pluspetrol, which leads the Camisea consortium that produces most of Peru's natural gas, declined to comment on potential lawsuits, but said it has fully complied with Peruvian law.
One of its concessions in Peru's southeastern jungle, known as Block 88, overlaps the Kugapakori-Nahua and Nanti indigenous reserve, established in 2003.
"Block 88 was created in the year 2000, before the reserve prohibited the granting of new rights in the territory," the company said in a statement. "It has been decreed that Camisea is in the nation's interest and a necessity."
Peru's rules governing natural resource extraction projects and tribal areas in the Amazon have, in some ways, evolved to give indigenous groups more protections as the government tries to balance competing priorities.
In a bid to defuse widespread social tensions over natural resources, Mr. Humala persuaded Congress in 2011 to pass a "consultation law" that requires the government and companies to talk with indigenous communities about how their lands are used.
But the law doesn't grant tribes veto power, and experts agree it would probably be impossible to apply it to benefit isolated tribes.
Peru's proven and certified reserves in Camisea total 10.3 trillion cubic feet, of which 8 trillion are in Block 88. The rest is in the adjacent Block 56.
Finding new gas deposits is a top goal of Mr. Humala, who took office promising to make gas cheaply available for everything from cars and power plants to petrochemical factories.
Mr. Humala's efforts to build new pipelines have at times been hobbled by lenders wanting to see more proven gas reserves.
Many new gas-fired power plants, built to add electricity to the fast-growing economy's grid, lack supply guarantees.
Mr. Ibanez, of Aidesep, said the 2003 law that established the indigenous reserve forbade new exploration and drilling beyond what was already under way.
The government says Mr. Ibanez's interpretation of the law goes too far.
"Authorizations for the start of different activities are made bit-by-bit," said Ivan Lanegra, the vice-minister of culture. "This does not amount to a new concession."
At the same time, he said the government was proceeding with caution. "With the steps we are taking I think there are enough guarantees to avoid problems" with inadvertent contact.
Potential delays in Camisea are not limited to tensions with indigenous groups.
Mr. Humala has replaced at least three defence ministers since taking office more than a year ago as the government struggles to stamp out what remains of a leftist insurgency that traffics in coca and cocaine near the gas fields.
In April the guerrillas took some three dozen Camisea contract workers hostage. They were released unharmed.
Part of Humala's gas plans include strengthening the state-run firm Petroperu in the style of Brazil's brawny Petrobras and steering more gas to domestic use instead of exporting it as a liquid.
"This is the future: Peruvian gas by Peruvians, for Peruvians and for the development of Peru," Mr. Humala has said.
Daniel Rodriguez, an anthropologist with the indigenous organization Fenamad in the Madre de Dios region, said he hopes the courts can halt new drilling.
He says outsiders can expose tribes to common diseases and that 60 per cent of the population of the Nahua tribe was wiped out by illness 30 years ago.
"This is not something we are making up, it is something that has already happened," he said.