Iran and major powers Tuesday effectively gave themselves until July 7 to reach a nuclear deal, the US State Department said as a midnight deadline approached in talks in Vienna with no agreement in sight.

"The P5+1 and Iran have decided to extend the measures under (2013 interim deal) until July 7 to allow more time for negotiations to reach a long-term solution," spokesperson Marie Harf said, adding that this meant that the talks were effectively extended to then.