An anti-austerity protest in the Greek city of Thessaloniki on Friday forced the cancellation of a military parade marking the country’s entry into World War II.
In several other Greek cities, officials were heckled but most of the parades went ahead as scheduled.
Debt-laden Greece is mired in its worst recession for four decades and unemployment levels have hit a record 16 percent.
Protesters chanted anti-government slogans in protest at spending cuts agreed with Greece’s international lenders of last resort: the European Commission, the European Central Bank and the IMF.
The national holiday of Ochi, or No, marks Greece’s rejection of of Italy’s ultimatum to surrender in 1940.
“We are once again saying NO to anyone who wants to come here and steal our country, be it the Germans or anyone else. We Say no and that’s final,” said one protester in Athens.
The government said the protesters only represented the views of a small minority of far-left political parties and trade unions.