Iranian Foreign Minister Mohammad Javad Zarif said Sunday that clinching a final nuclear deal with world powers is still "possible" despite a tough round of talks this week.
"Agreement is possible. But illusions need to go. Opportunity shouldn't be missed again like in 2005," Zarif said on Twitter, referring to Iran's long-stalled dispute with world powers over its suspect nuclear programme.
Iran and six world powers ended a fourth round of nuclear talks in Vienna on Friday with "no tangible progress".
Britain, China, France, Russia, the United States and Germany -- known as the P5+1 group -- want Iran to radically scale back its nuclear activities, making any dash for an atomic bomb virtually impossible and easily detectable.
The parties want to clinch a deal by July 20, when a November interim deal expires, under which Iran froze certain activities in return for some relief from crippling Western sanctions.
In return for further concessions, the Islamic republic, which denies seeking an atomic weapon, wants the lifting of all UN and Western sanctions, which have caused major damage to its economy.