An interim nuclear agreement between Iran and six major powers will be extended through Friday to provide more time for talks on a final agreement, the United States said Tuesday.
"We have made substantial progress in every area, but this work is highly technical and high stakes for all of the countries involved," said U.S. delegation spokeswoman Marie Harf.
"We are frankly more concerned about the quality of the deal than we are about the clock ..." Harf's statement said.
EU foreign policy chief Federica Mogherini said earlier Tuesday, "We are interpreting in a flexible way our deadline, which means that we are taking the time, the days we still need, to finalize the agreement," adding several difficult issues to resolve remain.