German Foreign Minister Heiko Maas today urged Iran to return to the Vienna negotiations on reviving a nuclear deal as soon as possible.

"If we don't want to jeopardize what we have achieved so far in Vienna we cannot stretch out the negotiations into eternity," Maas told journalists in Berlin.

"We expect Iran to return to the negotiating table in Vienna as soon as possible, and to do so with the necessary flexibility and readiness for compromise to strike a deal."