Black-clad demonstrators have hurled stones and fire bombs at police in front of the Greek parliament as tens of thousands rallied for a nationwide general strike to coincide with a vote on painful new austerity measures.

The clashes overshadowed the start of a 48-hour strike which shut down government departments, businesses and public services, as well as shops and bakeries. Flights were cancelled.

Al Jazeera's Andrew Simmons reports from Athens.