GENEVA — With PowerPoint slides and feel-good phrases, Iranian negotiators presented world powers on Tuesday with what they said was a plan to break a decade of deadlock over Tehran’s nuclear program, declaring the time had come to end the country’s “walk in the dark” of international isolation and crippling sanctions.

Neither Iran nor the six nations negotiating with it revealed details of the proposal. But their guarded comments indicated some progress had been made and a rare private meeting between Deputy Foreign Minister Abbas Araghchi and the chief U.S. negotiator, Wendy Sherman, suggested a better tone compared to previous encounters.

Speaking in English, Iranian Foreign Minister Mohammad Javad Zarif outlined the proposal, entitled “An End to the Unnecessary Crisis and a Beginning for Fresh Horizons.”

A member of one of the delegations meeting with Iran said the plan offered reductions in both the levels of uranium enrichment being conducted by Iran and the number of centrifuges doing the enrichment — a key demand of the six powers. He demanded anonymity because he was not authorized to divulge details.

Iran’s state TV, which closely reflects government views, said Tehran offered to discuss uranium enrichment levels. The report also said Iran proposed adopting the additional protocols of the U.N.’s nuclear treaty — effectively opening its nuclear facilities to wider inspection and monitoring — if the West recognizes Iran’s right to enrich uranium.

The Iranian presentation was followed in the afternoon by what European Union spokesman Michael Mann said were very detailed technical talks “for the first time.”