By Parisa Hafezi and John Irish DUBAI/PARIS (Reuters) -While rising U.S.-Iran tensions over Tehran's uranium enrichment jeopardize nuclear talks, three Iranian sources said on Tuesday that the clerical leadership lacks a clear fallback plan if efforts to resolve a decades-long dispute collapse.

Iranian Foreign Minister Abbas Araqchi said on Friday there was potential for progess in nuclear negotiations with the U.S. after mediator Oman made several proposals, adding that the talks were complicated and more discussions were needed.

DUBAI (Reuters) -Iranian and U.S. negotiators will resume talks on Friday in Rome to resolve a decades-long dispute over Tehran's nuclear ambitions, despite Iran's supreme leader warning that clinching a new deal might be insurmountable amid clashing red lines.