E.U. High Representative for Foreign Affairs Catherine Ashton, left, and Iranian Foreign Minister Mohammad Javad Zarif before the start of closed-door nuclear talks Monday at the United Nations offices in Geneva. Fabrice Coffrini/AFP/Getty Images

Six world powers — the United States, Russia, China, France, Britain and Germany — began formal talks with Iran on its nuclear program in Geneva on Tuesday with a presentation from Tehran that the Iranian delegation and a European Union spokesman said was well received.

Saying that Iran no longer wanted to "walk in the dark” of international isolation, Deputy Foreign Minister Abbas Araqchi told reporters that "the first reactions were good" to a blueprint laid out by Iran's Foreign Minister Javad Zarif to end the impasse over Tehran's nuclear program.

"We think that the proposal we have made has the capacity to make a breakthrough," Araqchi said.

A Geneva-based E.U. spokesman described Iran's initial proposal, which took the form of an hour-long PowerPoint presentation delivered on Tuesday morning, as "very useful" and added that "very technical discussions" were set to continue in the afternoon.

The meeting, which will extend through Wednesday, is the first such round of talks among the group since the election of reformist Iranian President Hassan Rouhani in June.

The meeting of the P5+1 — the five permanent members of the U.N. Security Council and Germany — follows recent signals from Iran that it wants to thaw relations with the U.S. The leaders of both countries have underscored the desirability of a deal on Iran's nuclear program.

Following Tuesday's session, the U.S. and Iran held a bilateral meeting on the sidelines that a State Department official called "useful."

Araqchi said the details of Iran's proposal, which Iran named "An End to the Unnecessary Crisis and a Beginning for Fresh Horizons" remained confidential, but he called the plan "completely realistic, balanced and logical."

Iranian state TV reported that Tehran offered to discuss uranium enrichment levels and proposed adopting the additional protocols of the U.N.'s nuclear treaty that would open the country's nuclear facilities up to wider inspection and monitoring if the West agreed to recognize Iran's right to enrich uranium.

A U.S. State Department official who was not authorized to disclose details of the meetings said that the afternoon session gave the six powers opportunity to probe for further details on Iran's plan.