SINANGOE - Armed with spears, their faces painted, members of the A'i Cofan community's indigenous guard prepare to patrol the banks of the Aguarico River in Ecuador's Amazon, ready to confiscate equipment and call in the police if they find miners on their ancestral land.

"We go down (the river) and document all the people who have entered," guard coordinator Nixon Andy, 24, said. "When we come across strangers on our territory we speak peacefully, but if there isn't respect there are authorities to whom we can report."

The guard's work is backed by the Constitutional Court, which in February ruled indigenous communities have the right to give prior consent to major extractive projects which take place in their territories or which could affect their way of life. They can veto both major mining and oil projects and small-scale informal production.

Legal success for the Cofan and challenges from other communities are undermining the investment ambitions of President Guillermo Lasso, who wants to attract foreign capital to mining projects.

The Cofan community, located in Sinangoe near the Colombian border, launched its fight against mining in 2017, arguing the industry was damaging the Aguarico, the main source of food for 53 families living along its banks.

Disagreement over the scope of the ruling remains, and the mining industry says the decision is an abrupt change which will affect investment and create more legal instability.

The mining industry and authorities say the ruling affects only future projects and should not halt those already cleared for development, like Chinese consortium Ecuagoldmining's Rio Blanco gold-silver project or Canadian company Dundee Precious Metals' Loma Larga gold project.

But indigenous communities and activist groups argue the decision applies to all projects, requiring companies to get consent as they move ahead to different stages.

Indigenous groups also have warned, including at a recent meeting of leaders from 500 communities across the Amazon basin, that rulings could be ineffectual without action from the government. Read full story

"Now if any community says no, the state must respect that decision and guarantee what we want for our home," said Cofan community leader Wider Guaramag. "We are the ones who suffer from mining."

The government - which has targeted a doubling in mining exports to $4-billion in the next three years, but not given a figure for how much investment could leave Ecuador if projects are halted - has said it is reviewing the decision.

"An extractive project rejected by the community could go ahead in exceptional circumstances, but subject to very clear rules," said Jorge Acero, a lawyer for the Amazon Frontlines advocacy group. "The risk is that the government considers that (situation) to be the rule when it's the exception."

As part of their decision, the court also ratified a ruling ordering gold concessions in Cofan territory be reversed because the community was not consulted.

"The court rulings upset the apple cart from one moment to the next," said Andres Ycaza, a lawyer for the private Ecuadorean Chamber of Mining. "In the Cofan case, it sets standards that are without a doubt an untimely change in the rules."

Indigenous communities in Peru - the world's second-largest producer of copper - are also fighting new projects, while large-scale mines in Colombia have been scuppered by referendums and rulings.

JUST THE BEGINNING
Ecuador's mining industry could benefit from political instability in Peru, a new leftist government in Chile and uncertainty over Colombian presidential elections, but the ruling may thwart that.

"Ecuador has an opportunity: its neighbors are not having a good time and mineral prices are rising," Ycaza said. "All these opportunities could disappear thanks to this."

Though the government has questioned the ruling, it is analyzing how to reverse concessions to comply, Deputy Minister of Mines Xavier Vera Grunauer told Reuters.

"We are concerned because the government is working hard to make the mining sector a pillar of the economy," Vera Grunauer said.

If a project is rejected by the community, the state must either adjust it to benefit the affected group or justify why it must go ahead despite opposition.

Other indigenous communities in Ecuador's Amazon like the Waorani and the Shuar Arutam are also fighting to block oil and mining and have filed a lawsuit before the court to stop Lasso's extractive plans.

While the Cofan have so far been one of few communities to successfully suspend mining in its territory, other threats remain.

The 26 young people who make up the indigenous guard - Ecuador's first - also confront loggers, poachers and fishermen.

The community has laws - recognized by the court - which allow it to order violators out, confiscate equipment and bring in police.

"It won't be easy to enter our territories because we are going to continue standing up," Alexandra Narvaez, the guard's first woman, told Reuters before the patrol.

"This struggle is just beginning."