Envoys: Iran, 6 powers remain deadlocked over uranium enrichment, other issues at nuke talks

The Iranian flag flies in front of a UN building where closed-door nuclear talks take place at the International Center in Vienna, Austria, Wednesday, June 18, 2014. (AP Photo/Ronald Zak) (The Associated Press)

The Iranian flag flies in front of a UN building where closed-door nuclear talks take place at the International Center in Vienna, Austria, Wednesday, June 18, 2014. (AP Photo/Ronald Zak) (The Associated Press)

Journalists wait in front of a poster of the Iran talks at the International Center in Vienna, where closed-door nuclear talks take place Wednesday, June 18, 2014. (AP Photo/Ronald Zak) (The Associated Press)

Diplomats following nuclear talks between Iran and six world powers say two days of negotiations have failed to narrow differences standing in the way of agreement by a July 20 target date.

The diplomats spoke Thursday ahead of a third day of planned meetings, with the possibility that they would wrap up the round early because of the lack of progress.

The key dispute centers on uranium enrichment, which can produce both reactor fuel and the fissile core of a warhead. The U.S. and its allies want deep cuts in Iran's enrichment program. Tehran, which says it does not want nuclear arms, is resisting.

Last month's round ended in deadlock. Two diplomats who talked to The Associated Press demanded anonymity because they are not authorized to discuss the confidential negotiations.