"Iran is a huge country, nearly four times the size of France and they began announcing the results within four hours, in past elections it's taken 24. It just seems to me the fix was in," says Juan Cole, Professor of Middle Eastern History at the University of Michigan.
Others point to particular results which appear unlikely.
For example, in Mr Mousavi's home province of East Azerbaijan, which is known to have fierce regional and ethnic loyalties to the reformist candidate, he polled far worse than expected.
And the liberal cleric Mehdi Karroubi polled 5% in Lorestan, despite having won 55% there in the first round of voting in 2005 when he also stood as a candidate.
"In some provinces like Khoresan or Mazandaran the number of people who voted exceeded the number of eligible voters in those provinces," points out Mr Khalaji.
12.05 01.06 02.06 03.06 04.06 05.06 06.06 07.06 08.06 09.06 10.06 11.06 12.06 01.07 02.07 03.07 04.07 05.07 06.07 07.07 08.07 09.07 10.07 11.07 12.07 01.08 02.08 03.08 04.08 05.08 06.08 07.08 09.08 10.08 11.08 12.08 01.09 02.09 03.09 04.09 05.09 06.09 07.09 08.09 09.09 10.09 11.09 12.09 01.10 02.10 03.10 04.10 05.10 06.10 07.10 08.10 09.10 10.10 11.10 12.10 01.11 02.11 03.11 04.11 05.11 08.11 09.11 10.11 11.11 01.12 05.12 07.12 08.12