You don't win when you deal with those people, they just make you think you did.
A deal on limiting Iran's nuclear programme in return for the lifting of sanctions has been reached at talks in Vienna, diplomats say.
The deal reportedly includes a compromise over the inspection of Iranian nuclear sites.
The EU announced a "final plenary" meeting at 08:30 GMT, followed by a news conference.
Six world powers including the US, Russia and the UK have been negotiating with Iran at the talks.
The so-called P5+1 - the US, UK, France, China and Russia plus Germany - want Iran to scale back its sensitive nuclear activities to ensure that it cannot build a nuclear weapon.
Iran, which wants crippling international sanctions lifted, has always insisted that its nuclear work is peaceful.
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A diplomat quoted by the Associated Press said the deal included a compromise over the inspection of nuclear sites. It would allow UN inspectors to monitor military sites, but Iran could challenge requests for access, the diplomat said.
Reuters cited two unnamed Iranian diplomats early on Tuesday as saying a deal had been reached.
"All the hard work has paid off and we sealed a deal. God bless our people," it quoted one of the diplomats as saying.