Looking stern and sounding angry Ayatollah Khamenei lashed out at Iran's opposition movement, once again calling its supporters "rioters" and "lackies" of Iran's foreign enemies. He also accused them of insulting and defiling the memory of Islamic Republic founder Ayatollah Ruhollah Khomeini.

The Iranian media has been waging a campaign for several days against student members of the opposition for allegedly burning a poster with the images of both Ayatollah Khomeini and Supreme Leader Ali Khamenei. Opposition members say the government staged the burnings to discredit them.

The Ayatollah complains rioters are being encouraged by enemies outside Iran to burn, defile and desecrate Khomeini's image. He says opposition supporters have taken the honorable portrait of Imam Khomeini and torched it, defiling his memory.

Ayatollah Khamenei also used his speech to a group of clerics to demand the opposition give up its claim, once and for all, that a June 12 presidential election was rigged, urging opposition leaders to put an end to agitation in the country:

He urges the opposition to remain calm. Many, he says, have turned the election into a campaign against the Islamic Republic. The election is over, he insists, and their charges of fraud were investigated, but they could not prove anything.

Despite the Ayatollah's call for calm, hundreds of opposition students demonstrated again Sunday at Tehran University. They denounced the government campaign against them for allegedly burning photos of Ayatollah Khomeini. Iranian police reportedly encircled the campus.

Iran's powerful Revolutionary Guard took the government campaign a step further, demanding on its website those responsible for burning photos be prosecuted and punished. Such a crime in Iran carries a penalty of several years in prison.

A number of opposition websites warn the Iranian government is preparing to crack down on the opposition and arrest its top leaders.

Exiled activist Mohsen Sazagara says Revolutionary Guard commanders have urged Supreme Leader Khamenei to arrest opposition leaders Mirhossein Mousavi and Mehdi Karroubi.

Ali Nourizadeh of the London-based Center for Arab and Iranian Studies argues the government campaign against the opposition is not gaining popular support, other than that of a handful of hardliners, and he questions if Ayatollah Khameini will dare arrest Mr. Mousavi for fear of a major backlash. "They wanted to make something out of nothing. They wanted to make demonstrations against the (opposition) Green Movement, and they burned Khomeini's picture-that is, you know, crossing all the red lines-but the response was nothing, just in Qom and some clergymen, some students, seminaries, and that is it. Therefore, that is not enough for them to have strong support and enough guts to arrest Mousavi. (Ayatollah Khamenei) may want couple of more days to see the response of the street and the response of the students, and we will see if Mousavi is going to be arrested," he says.

Mr. Mousavi's "Kalameh" website asked supporters to remain "alert," warning that "propaganda in the government-run media could lead to something new and unexpected."