"Most of them agree, but I still don't have the answer from the United States, who I understand have to discuss it, and we expect during this week to receive an answer," Borrell said in an interview with Spain's national broadcaster TVE.

Borrell said Iran has asked a few adjustments to the EU proposal - which was not made public - that followed 16 months of fitful, indirect U.S.-Iranian talks with the EU shuttling between the parties. He had said on Monday he considered Tehran's answer was "reasonable".

Iran has been negotiating with the five permanent members of the UN security council plus Germany and the EU to revive a 2015 agreement former President Donald Trump reneged on three years later.

Since then, the U.S. reinstated tough sanctions on Iran, which began breaching its limits on uranium enrichment.