Iranians regard the holiday as a chance to purify the soul for the new year, or Nowruz, which begins on March 21.

Opposition supporters say they may hold street protests to coincide with the event.

Iran's opposition used a religious holiday in late December to rally its supporters, holding massive demonstrations in the streets of Tehran. On that day, at least eight people were killed in clashes between security forces and demonstrators in the worst bloodshed since the height of the unrest last summer.

The turmoil erupted last June after Iran's disputed presidential election. The opposition claimed that its leader Mir Hossein Mousavi was the rightful winner and that hard-line President Mahmoud Ahmadinejad's win was fraudulent.