TEHRAN (Reuters) - Iran warned the opposition on Saturday against staging demonstrations after calls were posted on websites for a rally on Sunday to commemorate two people killed during protests this week, state media reported.

Opposition leaders Mirhossein Mousavi's and Mehdi Karoubi's websites have called for nationwide rallies on Sunday, which they also said were intended to show "decisive support to the pro-reform movement and its leaders."

"They will be confronted as per the law," the official IRNA news agency quoted Interior Minister Mostafa Mohammad Najjar as saying, when asked about planned opposition rallies.

The authorities, seeking to avoid revival of the mass anti- government rallies that erupted after the disputed 2009 presidential vote, say they will confront any "illegal" gatherings by the opposition, state media reported.

Two people were killed and dozens arrested on Monday when thousands of opposition supporters in Tehran and other cities took to the streets in defiance of a heavy security presence to back uprisings in Egypt and Tunisia, that toppled their leaders.

An opposition website said at least 1,500 people were arrested while taking part in the banned protests and many wounded in clashes with security forces. Police said dozens were arrested and nine policemen were injured in Monday's rallies.

Mousavi's "kaleme" website said the Monday rally, the first big show of opposition on the streets since December 2009, showed Iran's pro-democracy movement was still alive.

Mousavi and Karoubi, who both lost to Ahmadinejad in the vote, have been placed under house arrest after calling for the rally.

Hardliners, including members of parliament, have urged the judiciary to hand down death penalties to opposition leaders.

"If you have the courage, put me on trial, but on a public trial and allow media to report what I say in that trial," Karoubi's website Sahamnews reported him as saying in response.

Authorities have called on the Iranian people to "exercise vigilance in regard to the likelihood of mischief and plots by "the enemy's agents and hypocrites."

Iran's hardline rulers accuse the opposition leaders of being part of a Western plot to overthrow the Islamic system. The claim has been denied by the opposition leaders.

Iran's top authority Supreme Leader Ayatollah Ali Khamenei has called the uprisings in Egypt and Tunisia against secular, Western-allied rulers an "Islamic awakening," akin to Iran's revolution that overthrew the U.S.-backed shah.

But the opposition says events in Tunisia and Egypt mirror their own protests after the 2009 vote which they say was rigged to secure President Ahmadinejad's re-election, an allegation the authorities deny.

(Editing by Michael Roddy)

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