Tehran: Scores of Iranian security forces were deployed in the streets of Tehran on Monday to prevent a planned opposition rally in solidarity with popular uprisings in Egypt and Tunisia that toppled their presidents, witnesses said.

The day is likely to be a test of strength for the reformist opposition, which has not taken to the streets since December 2009, when eight people were killed. Iranian security forces are still unlikely to hesitate to use all means to stop any protest.

Opposition leaders Mirhossein Mousavi and Mehdi Karroubi took advantage of official Iranian backing for the huge Arab street protests to call their own demonstrations in support, but authorities refused their request.

The opposition nevertheless renewed the call for the rally. Iranian authorities have warned the opposition to avoid creating a "security crisis" by reviving protests that erupted after the vote, the biggest unrest in Iran since the 1979 revolution.

"There are dozens of police and security forces in Vali-ye Asr Avenue ... They have blocked entrances of metro stations in the area," a witness told Reuters by telephone, referring to a large thoroughfare that cuts through Tehran.

Another witness said police cars with windows covered by black curtains were parked near Tehran's notorious Evin prison.

Mousavi's website, Kaleme, said security forces had set up a roadblock, refusing access to the opposition leader's residence in southern Tehran. It said both mobile and landline telephone communications with Mousavi's house were cut.

"It seems these newly-set restrictions are aimed at preventing Mousavi and his wife (Zahra Rahnavard) from attending the rally," Kaleme said. Plainclothes police stopped Rahnavard leaving the house, Karroubi's Sahamnews website reported.

Iranian Supreme Leader Ayatollah Ali Khamenei called the uprisings in Egypt and Tunisia an "Islamic awakening," akin to the 1979 revolution that overthrew the U.S.-backed shah.

But the opposition see the unrest as being more similar to their own protests following the June 2009 election which they say was rigged in favor of President Mahmoud Ahmadinejad.

The Revolutionary Guards, fiercely loyal to Khamenei, put down the 2009 protests. Two people were hanged and scores of opposition supporters jailed. The last mass demonstration was held in December 2009.

"ALLAHU AKBAR"

Iranian state television repeatedly showed footage of a state-organized rally on Friday to mark the 32nd anniversary of the Islamic revolution. But cries of "Allahu Akbar" (God is Greatest) were heard from rooftops overnight, a move urged by the opposition, copying tactics used by revolutionaries in 1979.

Authorities deny doctoring the 2009 election results and accuse opposition leaders of being part of a Western plot to overthrow the Islamic system.

"They are incapable of doing a damn thing," the hardline Kayhan newspaper quoted Intelligence Minister Heidar Moslehi as saying, echoing words used by revolutionary leader Ayatollah Ruhollah Khomeini to refer to the United States.

The opposition is "guided by Iran's enemies abroad," Moslehi said.

Mousavi says the freedom movement is alive. But his campaign is fading as many Iranians feel the former prime minister lacks the courage to confront the establishment from which he sprang. The opposition denies having any links to the enemies abroad.

Many Iranians critical of the government now seem unwilling to risk violence or arrest with displays of dissent. But the opposition's call has gained momentum on social networking websites, with more than 56,000 people pledging to participate on one protest group's Facebook page.