European Union foreign policy chief Federica Mogherini said negotiations would continue, but denied the deadline had been extended.
The US State Department meanwhile confirmed that the interim agreement with Iran which had been signed in late 2013 would now carry on until July 10.
Foreign ministers from the P+5 group had continued discussions on Tuesday, but did not hold direct talks with Iran’s foreign minister Mohammed Javad Zarif.
The State Department said it hoped a “comprehensive agreement” could be reached and said Secretary of State John Kerry would stay in Vienna to continue the discussions.
