Updated

Thousands of Greeks are expected to march to the US Embassy in Athens to mark the anniversary of the 1973 crackdown on a student uprising against the military dictatorship then ruling Greece.

The annual march from the gates of the Polytechnic building in downtown Athens to the embassy often attracts tens of thousands of demonstrators. Police have said more than 5,000 officers will be on duty for Friday's demonstration, which commemorates those who died in the crackdown on the uprising against the 1967-74 junta.

Ahead of the anniversary, some anarchist groups occupied the polytechnic building and distributed fliers urging nearby residents to attack police by dropping flower pots from their balconies.