Greek riot police fired tear gas to disperse protesters throwing rocks and Molotov cocktails outside the U.S. Embassy on Monday during an annual march to mark the anniversary of a student uprising.

Three police were injured in the clashes, while 11 protesters were detained, authorities said. Damage was reported at two bank branches in central Athens, a car showroom and to three vehicles.

About 10,000 people braved a thunderstorm to mark the 35th anniversary of the student uprising against the military dictatorship that ruled Greece from 1967-74. They marched to the U.S. Embassy to protest Washington's support for the junta at the time.

A group of about 100 youths broke away from the peaceful rally, throwing rocks and firebombs at riot police deployed outside the embassy building. Heavy rainfall quickly extinguished the fire from the petrol bombs, and the youths dispersed after police responded with tear gas and gave chase.

Police had deployed 8,000 officers in Athens and an additional 1,500 to 2,000 in Greece's No. 2 city, Thessaloniki. Major roads in both cities were closed.

The annual marches are often marred by violence.

The U.S. Embassy had warned American citizens to avoid the demonstration areas and instructed U.S. diplomats in some areas of Athens to remain at home. Both the embassy in Athens and the consulate in Thessaloniki closed early.

The exact death toll from the events in November 1973 has never been definitively established, but some say dozens of people were killed in the days around the student uprising.