Many analysts had already called the target unfeasible, citing world No. 1 copper producer Chile's ballooning energy problems, dwindling ore grades and volatile world copper prices that may cause firms to reconsider projects.

On Tuesday, Chile's top court rejected the planned $5 billion Central Castilla thermoelectric power plant, citing environmental reasons, potentially jeopardizing a string of new mines planned in the mineral-rich Atacama region.

"The portfolio of $100 billion appears very ambitious, clearly it's a little optimistic to make it materialize within the timeframe initially forecast," Codelco's CEO said during a news conference.

"Indeed some projects have already been delayed and likely won't be achieved in line with what was originally programmed," he added.

Chile, once Latin America's investor darling, is also experiencing a rise in environmental and social opposition to mega projects that is gaining traction in courtrooms.

While mining helped Chile's economy grow 5.4 percent in the first half of this year, the country has the highest level of income inequality among the 34 OECD countries, according to a report by the body last year, and many Chileans feel they have been left out of the country's copper boom.

Chile's government will on Thursday send a bill to Congress intended to connect its two main energy grids to soothe criticism, soften high energy prices and bolster the country's shaky transmission system.

Cerro Casale, owned by Barrick Gold (>> Barrick Gold Corp) and Kinross (>> Kinross Gold Corp.), Lumina Copper's (>> Lumina Copper Corp) Caserones mine and Barrick's Pascua Lama mine are gearing up to operate in the area near where Castilla was planned.

But the rejection of Castilla may lead to delays in Codelco's small Salvador project as energy prices will be hard to stomach, Keller said in an interview with Chile's Diario Financiero on Wednesday.

Keller is overseeing the state miner's own challenging investment plans to boost copper output to over 2 million tonnes from around 1.7 million tonnes.

More than $22 billion and over 8,000 megawatts in energy investment in Chile have been suspended, according to Libertad y Desarrollo, a conservative Chilean think-tank.

Brazilian billionaire Eike Batista, whose MPX Energia SA (>> MPX Energia SA) was spearheading the Castilla project, reportedly said via Twitter that investing in Chile "was becoming impossible," according to local media, which added that the tweet was later deleted.

(Reporting by Anthony Esposito, writing by Alexandra Ulmer, editing by Gary Crosse.)