From a WSJ report:

On his Web site, Mr. Mousavi said his position that election results were rigged against him hasn’t changed. Mr. Mousavi and his supporters have openly defied the orders of Iran’s Supreme Leader, Ayatollah Ali Khamenei, who called during Friday prayer sermons for the protests to end and for the election dispute be settled by legal channels.
The Web site called for a general strike and suggested targeting the flow of oil. Mr. Mousavi and two other challengers have alleged more than 600 specific instances of violations, according to the Guardian Council, a top clerical oversight board that oversees elections.
In a report released Sunday, Chatham House, a London think tank, raised questions about some of the results, using publicly available census data and results published by the ministry of interior for elections in 2005 and 2009. Researchers determined that in two conservative-leaning provinces, voter turnout exceeded 100%.
The report showed that in a third of provinces, Mr. Ahmadinejad would have had to capture all of his traditional voter base, plus a high percentage of voters who previously didn’t support him, to reach his purported total.