EU diplomats have said they are concerned Tehran's new negotiating team may make new demands beyond the scope of what had already been agreed.

Iran is not ready to return to talks with world powers over its nuclear program yet and its new negotiating team wants to discuss the texts that will be put forward when it meets with the EU in Brussels in the next few weeks, a senior EU official said on Friday.

EU political director Enrique Mora, the chief coordinator for the talks, was in Tehran on Thursday to meet members of Iran's nuclear-negotiating team, four months after discussions broke off between Iran and world powers.

Iranian President Ebrahim Raisi has so far refused to resume indirect talks with the United States in Vienna on both sides returning to compliance with the deal, under which Iran curbed its nuclear program in return for economic sanctions relief.