"We are very close but there are still some issues pending," Borrell told reporters on the sidelines of the Doha Forum in Qatar. "I cannot tell you when or how, but it is a matter of days."
The EU coordinator for the talks, Enrique Mora, traveled to Tehran on Saturday and said he was hoping to close gaps in the negotiations.
"We are at 95 percent but the last five percent is critical," said Borrell, the EU's high representative for foreign affairs, who added the last major obstacle was removed when Russia ended its opposition to a deal earlier this month.
"We want to prevent the nuclear program from advancing. I will be very disappointed if it does not happen," he stated.
Iran has gradually scaled back its compliance with the 2015 deal it signed with world powers, in response to former US President Donald Trump’s withdrawal from the agreement in May of 2018, but has held several rounds of indirect talks with the US on a return to the agreement.
Negotiations nearly reached completion earlier this month before Moscow demanded that its trade with Iran be exempted from Western sanctions over Ukraine, throwing the process into disarray.
US State Department spokesman Ned Price said this past week that Washington has a "Plan B" if a nuclear deal with Iran is not reached.
"The onus is on Tehran to make decisions that it might consider difficult," Price told reporters.
"In fact we are preparing equally for scenarios with and without a mutual return to full implementation of the JCPOA," he added, referring to the formal name of the 2015 deal, the Joint Comprehensive Plan of Action.
Later, Iran’s Foreign Minister, Hossein Amir-Abdollahian, claimed his country is ready to reach a lasting agreement with world powers and blamed the latest failure to revive the 2015 nuclear deal on an allegedly “unrealistic vision” by the United States.
