Iranian students hold a caricature of US President Barack Obama during a rally outside the former US embassy in Tehran November 4, 2009.

TEHRAN: Tens of thousands of Iranians held demonstrations on Wednesday across the country to mark the 30th anniversary of the seizure of the US embassy in Tehran by Iranian students.

In Tehran, the demonstrators gathered outside the former US embassy in central Tehran, carrying placards expressing their hatred of the "arrogant powers" and shouting anti-US and anti-Israel slogans.

He said the seizure of the US embassy in Tehran by Iranian students in 1979 was "the right thing to do" because Washington used the embassy for espionage activities.

Also on Wednesday, some supporters of Iran's opposition leader Mirhossein Mousavi clashed with Iranian police in Tehran when they attempted to stage an anti-government protest, witnesses said.

The US embassy was stormed by Iranian students on November 4, 1979 and its personnel were held hostage for 444 days. The US broke off diplomatic relations with Iran in 1980 and their ties have remained severed ever since.

Since the 1979 takeover of the US embassy in Tehran, Iranians have been celebrating the occasion every year by holding rallies on the anniversary and marking it as the "National Day against the Global Arrogance."