ATHENS (AFP) - Police and masked youths clashed in Athens on Wednesday during a nationwide strike in protest at a new round of austerity cuts introduced in return for crucial EU-IMF loans.

Gangs of youths threw firebombs, smashed windows and set fire to garbage on the sidelines of the demonstration near luxury hotels on the capital's central Syntagma square.

The police responded by firing tear gas and stun grenades to disperse them.

Dozens of people were detained, according to a police source, as crowds moved towards the capital's other central square, Omonia, booing and throwing plastic bottles at the special forces that were present.

The protests rallied striking civil servants and private sector workers as well as students and pensioners, who have all been hit by previous rounds of cutbacks in the debt-laden eurozone country.

Nearly 34,000 people marched in Athens and another 18,000 in Thessaloniki, according to the police, in the first general strike to be held since the new government took office in June, bringing the country to a standstill.

Flights, train services and ferries were halted while the public sector, including museums, shut down.