Tehran:
Eyewitnesses report that sporadic clashes have erupted in Central Tehran's Enghelab or Revolution Square between security forces and Opposition protesters.
The demonstrators were chanting "death to the dictator," referring to the country's hard-line president that the Opposition believes was re-elected through fraud in 2009.
Iran's Opposition called for a demonstration on Monday in sympathy with a popular uprising in Egypt that forced Hosni Mubarak to resign as President.
Tear gas was used to disperse the protesters, but witnesses report that many have still gathered in nearby Enghelab Avenue.
Iran's security forces cut phone lines and blockaded the home of an Opposition leader in attempts to stop him attending the planned rally.