European Union foreign policy chief Josep Borrell met Iranian Foreign Minister Hossein Amir-Abdollahian on Saturday after arriving in Tehran for talks in an effort to revive the 2015 Iran nuclear deal.

The surprise visit by Borrell, who arrived in the Iranian capital on Friday night, is aimed at getting the talks back on track three months after they stalled amid differences between Iran and the United States.

"Diplomacy is the only way to go back to full implementation of the deal and to reverse current tensions," Borrell tweeted.

Borrell went into a meeting with Amir-Abdollahian in the morning and was expected to hold talks with other Iranian officials later in the day, according to the official Iranian news agency IRNA.