Videos from Iran appear to show a large political protest taking place during a funeral for the late reformist cleric Ayatollah Jalaluddin Taheri.
Reuters described tens of thousands of people calling for freedom for jailed opposition leaders.
Many anti-government activists were arrested in the brutal government crackdown on opposition activity that followed the country's disputed 2009 presidential election. The opposition maintains the election results were rigged; the authorities deny it.
But public anger over the tightly-contested vote threatened to undermine the regime — the demonstrations that followed were the largest mass riots recorded since the nation's 1979 Islamic revolution.
Taheri was a vocal critic of the regime and also condemned the 2009 election results, which proclaimed Mahmoud Ahmadinejad the victor.
According to the Iranian opposition news website Kaleme: "The funeral service for Ayatollah Taheri in the city of Isfahan was accompanied by slogans in support of detained leaders of the Green movement." The opposition Green movement arose in support of former presidential candidate Mir Hossain Mousavi, who has since been put under house arrest.
Some think anti-establishment activity in Iran has been strengthening on the sly. Afshin Shahi of Britain's Exeter University recently argued in Foreign Policy that Iran "is in the throes of an unprecedented sexual revolution," writing:
"While not necessarily positive or negative, Iran's sexual revolution is certainly unprecedented. Social attitudes have changed so much in the last few decades that many members of the Iranian diaspora are shellshocked when they visit the country: "These days Tehran makes London look like a conservative city," a British-Iranian acquaintance recently told me upon returning from Tehran. When it comes to sexual mores, Iran is indeed moving in the direction of Britain and the United States — and fast. "
Iranians go to the polls to elect a new president on June 14.