Tehran

The negotiations entered their 15th day Saturday with no indications of major progress after three extensions and four target dates for a deal, and diplomats said it remained unclear whether an agreement could be reached by Monday, the latest deadline.

Iran and the U.S. have threatened to walk away unless the other side makes concessions. Although it was unclear whether Ayatollah Ali Khamenei was preparing the ground for the failure of the talks, his comments were likely to add to skepticism over the outcome at the negotiating table.

Speaking on the eve of a belated target date for a complete agreement, a senior Iranian official said his country and the six world powers it is negotiating with are also working on a U.N. resolution that endorses any future nuclear deal.

Lifting the arms embargo would be separate from a long-term accord that foresees limits on Iran's nuclear programs in exchange for relief from crippling sanctions on the Islamic Republic.