He has for the first time publicly acknowledged that the trial was staged.
Abtahi -- a close aide to former President Mohammad Khatami who campaigned for reformist cleric Mehdi Karrubi before last year's presidential vote -- had criticized the reformists in televised confessions and said that they tried to insinuate that there was fraud in the election.
His family has said that he had been put under pressure to make false confessions.
Abtahi was released last November and had so far remained silent about his time in jail and his confessions.
On August 1, he posted a picture of himself at last year's trial on his Facebook page (screenshot here) and wrote:
"A year ago on such a day we had a trial, we had practiced the day before. What a day it was...."
Even before Abtahi's public acknowledgment, there was little doubt about the nature of the series of trials last year, which had been dismissed by opposition figures and others as "a farce " and "show trial" aimed at legitimizing President Mahmud Ahmadinejad's victory.
Abtahi's note drew more than 200 comments that included expressions of support and concern that his note might cause him trouble, and also some criticism on his Facebook page. His note was also posted and commented on in blogs.
Here are some of the reactions:
"The trial was an embarrassment for the establishment. We will be pushing for reforms."
"Thank you for responding to people after one year."
"Bravo! But you're making comments that might be dangerous for you."
"Someone who gets involved in politics should be ready for anything; there is no place for cowards in the world of politics."
"We know it was staged on the same day, don't give an excuse to [the authorities]."
There has so far been no reaction from government officials and hard-liners to Abtahi's note.
-- Golnaz Esfandiari