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Chile and the United States are working on a nuclear energy accord in advance of President Barack Obama's visit to the region in March, the U.S. Ambassador to Chile said Friday.

Former Chilean President Michelle Bachelet had ruled out developing nuclear energy during her term, but it's clearly back on the agenda under current President Sebastian Pinera, with Chile's robust economic growth making new sources of energy ever more critical.

"The decisions about what Chile's energy future looks like and whether nuclear energy is part of that mix is the Chileans' to make, and they haven't made any decisions we're aware of, but we stand ready to help," Ambassador Alejandro Wolff told The Associated Press by telephone from Santiago.

"We happen to be working at the moment on a memo of understanding on nuclear cooperation, and I hope that's one of the things we'd be able to announce or talk about," he added.

That help would most likely come in the form of technical advice on handling dangerous nuclear materials, Wolff added. Chile has a small nuclear program with two research reactors now used to create material for medical tests, and it worked closely with U.S. engineers to rid itself of the last of its weapons-grade, highly enriched uranium from those reactors.

Developing other reactors to generate energy would require considerable investments in infrastructure and expertise, as well as political support — decisions that would involve years of planning. But Wolff said it's one aspect of the bilateral relationship that "probably has promise."

Given the huge costs, risks to investors and likelihood of popular rejection of nuclear energy, some Chilean environmentalists said Friday that the country should focus instead on existing agreements with the U.S. and the state of California to develop renewable energy technology.

"The truth is it's not very possible to achieve the security needed (for nuclear energy) in countries as earthquake-prone as Chile," Sara Larrain, who directs the Sustainable Chile organization, told the AP. "There's an enormous nuclear energy lobby in Washington that wants a foothold in Latin America. They're desperate because they haven't been able to have a new develop new nuclear power plans in the United States for years," she said.

Nuclear energy is in vogue in South America. In Santiago, ministers of Chile and Argentina met this week, with developing nuclear energy and links between the two countries' electricity grids as part of their shared agenda.

And on Monday, during her first visit as Brazil's president to Argentina, Dilma Rouseff plans to sign an accord establishing a shared project with Argentina to build another nuclear energy reactor in each country.

"Argentina has experience in the construction of reactors and Brazil has experience managing nuclear energy," Brazilian diplomat Antonio Simoes said Friday.

In Buenos Aires, the daily La Nacion reported that Obama's decision to skip Argentina in his first visit to South America upset the government of President Cristina Fernandez. But Argentine Foreign Minister Hector Timmerman dismissed the report as "the silliness of a soap opera" and insisted that the government's relationship remains dynamic and positive.

"The simple reality is that you can't visit all the countries," said Wolff, who also suggested that with presidential elections planned for Oct. 23 in Argentina, the timing wasn't right.

"It's important also to know that when there are other countries experiencing their own political calendars with elections and the like, visits take a different context if they take place in a pre-electoral period," Wolff said.

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Associated Press Writer Marco Sibaja in Brasilia, Brazil contributed to this story.