WASHINGTON, Oct 12 (Reuters) - The Washington Post on Monday denounced the espionage conviction of the newspaper's American-born Tehran correspondent as an "outrageous injustice" and urged Iran's leaders to overturn it.

Jason Rezaian, who was arrested in July 2014, had 20 days to appeal the verdict, the Iranian news service ISNA cited a judiciary spokesman as saying.

Washington Post Executive Editor Martin Baron said the paper, Rezaian's family and his lawyer in Iran were pursuing an appeal. He said no sentence for Rezaian had been announced.

"The guilty verdict announced by Iran in the trial of the Washington Post's Jason Rezaian represents an outrageous injustice," Baron said.

"Iran has behaved unconscionably throughout this case ... The contemptible end to this 'judicial process' leaves Iran's senior leaders with an obligation to right this grievous wrong."

The case has been a sensitive issue for Washington and Tehran and Post officials said Rezaian had been used as a bargaining chip.

Iran had accused Rezaian, 39, of collecting confidential information and giving it to hostile governments, writing a letter to U.S. President Barack Obama and acting against national security - charges that the Post dismissed as absurd.

(Writing by Bill Trott; Editing by Bernadette Baum) ((bill.trott@thomsonreuters.com; + 1 202 898 8322; Reuters Messaging: bill.trott.thomsonreuters.com@reuters.net))

Keywords: IRAN USA/TRIAL POST