Federica Mogherini has hailed the nuclear accord as a "sign of hope for the entire world."

AFP/Brussels

EU foreign affairs chief Federica Mogherini will visit Iran and Saudi Arabia next week following the agreement she helped broker with Tehran on its contested nuclear programme, her office said on Thursday.

The talks in Saudi Arabia on Monday will cover "regional issues, in the aftermath of the agreement reached on July 14 on the Iranian nuclear issue, as well as international issues of common interest," a statement said.

In Iran, Mogherini's visit on Tuesday "will provide an opportunity for exchanges on the implementation of the agreement, on which the High Representative will continue to play a coordinating role, and on regional and bilateral issues," the statement added.

The EU played a leading role in talks between Britain, China, France, Russia, the US, Germany and Iran, holding the ring during years of tortured negotiations which finally produced an accord last week on preventing Tehran from acquiring a nuclear weapon.

In return, the powers agreed to lift damaging economic sanctions as long as Iran sticks to a deal they hope will eventually normalise ties with Tehran after years of intense distrust over its nuclear programme.

Mogherini hailed the accord as a "sign of hope for the entire world."

"It is a decision that can open the way to a new chapter in international relations and show that diplomacy, coordination, cooperation can overcome decades of tensions and confrontation," she said after the talks concluded in Vienna.

Saudi Arabia and Iran are locked in a dangerous stand-off from Syria to Iraq to Yemen, driving fears in Brussels of regional instability and conflict.

German Vice Chancellor Sigmar Gabriel visited Iran earlier this week to push for improved ties but his talks were marked by sharp differences over Israel, which Iran does not recognise.