TEHRAN, Iran — Iran’s official news agency says a court has sentenced three prominent political activists to six years in prison each for involvement in the country’s post-election turmoil. Monday’s report by IRNA says the activists — Mohsen Mirdamadi, Mostafa Tajzadeh and Davood Soleimani — were convicted of spreading propaganda against Iran. The court also banned them from any kind of political activity for 10 years. The three are among more than 100 opposition figures put on a mass trial in the wake of the disputed June presidential elections. The trial has led to a dozen death sentences so far. The Iranian opposition, led by Mir Hossein Mousavi, charges that the election was fraudulent and that President Mahmoud Ahmadinejad was not the rightful winner.