The Trump administration is prepared to allow Iran to have a civil nuclear program that relies exclusively on imported nuclear fuel, Secretary of State Marco Rubio said, outlining a possible compromise with Tehran aimed at preventing it from building a nuclear weapon.

However, Iran has already made clear that its right to enrich uranium is not negotiable. When asked about Rubio's comments, a senior Iranian official, close to Iran's negotiating team, again said on Wednesday "zero enrichment is unacceptable.

U.S. talks that were supposed to take place on Wednesday will be shifted to Saturday, Tehran's foreign ministry spokesperson said, with a third round of high-level nuclear talks due on the same day in Oman.