President Ollanta Humala, who campaigned this year on a promise to end conflicts over mining in Peru, has instead seen a deepening of the troubles.

The latest example is the fight over the giant Minas Conga copper-gold project in northern Peru. Despite an end to violent protests there against the greenfield project after Minera Yanacocha SRL suspended work, opponents continue to push for a definitive canceling of Minas Conga, Peru's biggest mining project.

In a report Wednesday, BofA Merrill Lynch said recent protests have threatened the security of mining investments in Peru, which it called a key driver of recent growth.

"We estimate that a halt to new mining investments would shave off 2.9 percentage points from GDP growth during the next two years," it said.

In the last ten years the number of mining concessions in Peru--one of the world's largest producers of gold, copper, silver and zinc--have doubled, while government policies to avoid conflicts haven't been developed, non-government organizations say.

The nation's ombudsman says there were 227 active conflicts tied to mining in October this year.

"Four months into the new government of Ollanta Humala there have been a number of conflicts that have reached the crisis stage. The question is why nothing has been done to avoid this," said Emma Gomez, deputy director of non-governmental organization CooperAccion, on Wednesday.

Anti-mining activists are meanwhile vowing to continue with their opposition to the Minas Conga project, being developed by Minera Yanacocha, which already runs a large gold mine in the region.

Yanacocha is 51.35% owned by Newmont Mining Corp. (NEM), Compania de Minas Buenaventura SAA (BVN, BUENAVC1.VL) has a 43.65% stake and the International Finance Corp. owns the remainder.

Anti-mining activists are also threatening to try to stop other large scale projects in the Cajamarca district, where Minas Conga is located.

Minas Conga is only the latest in a series of mining projects in Peru that have run into opposition, often driven by local politicians seeking voter support.

Southern Copper Corp. (SCCO) had to suspend work on its Tia Maria copper project earlier this year, while the government of ex-President Alan Garcia suspended work on a project run by Bear Creek Mining Corp. (BCEKF, BCM.V) in southern Peru following protests.

Conga was scheduled to begin production in 2015, with average output during the first five years of 580,000 ounces to 680,000 ounces of gold and 155 million to 235 million pounds of copper.

-By Robert Kozak, Dow Jones Newswires; 511 99927 7269; peru@dowjones.com