Athens - Greek anarchist groups carried out arson attacks on four bank branches in Athens overnight to Wednesday, Greek media reported.
Household gas canisters were set alight at the entrances to the banks, causing considerable damage, according to the reports.
A police officer was seriously injured in a clash between police and anarchists in Athens Tuesday evening.
Police used tear gas and batons to disperse the crowds who threw Molotov cocktails at the officers.
The Greek police fear further riots as November 17 approaches.
On November 17, 1973, a student uprising against the military which ruled Greece from 1967 to 1974 was suppressed violently.
Street battles between anarchists and police in Athens take place around this time every year.