Greek police have fired tear gas to disperse thousands of demonstrators protesting the visit of U.S. Secretary of State Condoleezza Rice.
Riot squads used several rounds of tear gas in Athens Tuesday to stop protesters from hurling gasoline bombs and rocks at authorities.
The Greek Communist Party and anti-war activists organized the anti-American demonstrations.
Rice is meeting Greek Prime Minister Costas Karamanlis and her Greek counterpart Dora Bakoyanni in Athens.
They are expected to discuss ways to end the 32-year-old Greek-Turkish split on the island of Cyprus.
Visits by U.S. officials are often met with protests in Greece.
Former Secretary of State Colin Powell canceled a visit to the Athens Olympics in 2004 because of concerns about protests.
Rice travels next to Turkey and Bulgaria on her European tour.
In Turkey, Rice will visit the U.S. embassy in Ankara to reaffirm Turkey's importance to the U.S. as a NATO ally.
She is expected to sign a defense cooperation agreement in Bulgaria and attend a NATO foreign minister' meeting.
Some information for this report was provided by AP and Reuters.