Marathon talks between Iran and major powers towards a historic nuclear deal have run into the early hours of Tuesday as signs grew that an agreement might be imminent.
Different delegations at the negotiations advised reporters in a packed press tent in Vienna to stay up all night and be ready for an early morning news conference.
US State Department spokeswoman Marie Harf and EU spokeswoman Catherine Ray both said however in identical tweets that there were "all kinds of unfounded rumours on the schedule".
The P5+1 - the United States, Russia, China, Britain, France and Germany - have been trying for the past 17 days to nail down an accord to end a 13-year stand-off over Iran's nuclear program.
The mooted deal would sharply curb Iran's nuclear program and impose strict UN inspections to make any drive to make nuclear weapons all but impossible and easily detectable.
In return the web of UN and Western sanctions choking Iranian oil exports and the economy of the 78-million-strong country would be progressively lifted.
The diplomatic push began when Iranian President Hassan Rouhani came to power in 2013. In November that year an interim deal was agreed but two deadlines in 2014 for a lasting accord were missed.
Then in April, the parties scored a major breakthrough by agreeing the main outlines of an accord, aiming to finalise it by June 30, a deadline since pushed back twice.
Since April, legions of legal and technical experts have made great strides working out the nuts and bolts of how the highly ambitious and technical agreement will work.
But the talks have stumbled on the exact timing and pace of sanctions relief and Iran's desire to have a UN conventional arms embargo lifted.
The White House said on Monday that the marathon discussions in Vienna had "made genuine progress".
"But there continues to be some sticking points that remain unresolved," White House spokesman Josh Earnest told reporters in Washington.
He said the United States and its partners did not want to rush the final stages of the lengthy talks.
If a deal can be sewn up, the prospect of a subsequent possible thawing of US-Iranian relations unsettles many in the Middle East, however.
These include Shiite Iran's Sunni-ruled rivals Saudi Arabia and other Gulf monarchies who see Tehran as a destabilising influence in the region.
Israel, widely assumed to have nuclear weapons itself, is also deeply concerned, complaining that the proposed deal will fail to stop its arch foe getting the bomb.