Iran and world powers have begun a second day of talks in Vienna over Iran's nuclear program.
Iranian Foreign Minister Mohammed Javad Zarif said the talks are going "well" and that he is optimistic Tehran and the six world powers can reach a broad settlement by a July 20 deadline.
But senior Iranian negotiator Abbas Araqchi said it was "too early" to draft a permanent agreement. He said the next round of talks is scheduled for April 7-8.
The meeting is taking place amid Western-Russian tensions over Ukraine, raising fears the world powers' unity could be weakened.
Michael Mann, a spokesman for the world powers' chief negotiator and EU foreign policy chief, Catherine Ashton, said on March 18 he has seen "no negative effect" on the Iran talks.
The negotiations are aimed at reaching a long-term settlement over Western allegations Iran is seeking nuclear weapons.
Iran denies any such weapons program.
The discussions come within the framework of a temporary agreement that limited Iran's nuclear activities in exchange for some sanctions relief.
The temporary accord expires in July but is renewable.
Based on reporting by Reuters and AP