Greek riot police have stormed a train depot in Athens to disperse subway staff defying government orders to end their strike.
The move intensifies a confrontation that has paralysed public transport in the city for nine days.
The capital's subway lines remain closed as most subway workers continue a strike against wage cuts.
However, some were back on the job after being served the orders to return to work or face arrest.
The showdown has turned into the latest test for Greece's fragile three-party ruling coalition.
The government is facing down unions to try to implement austerity measures demanded by foreign lenders as the price for bailout funds.
Scuffles broke out when police forced their way through a metal gate at around 4am at the depot, where 90 workers had gathered overnight in protest.
At least ten workers were detained and then released, an official said on condition of anonymity.
Prime Minister Antonis Samaras's government has taken a hard line on the strike despite criticism from the smallest party in his three-party government.
"When labour action is judged illegal and abusive, the law has to be implemented. Everyone has made sacrifices and no one can ask to be made an exception," government spokesman Simos Kedikoglou told state television.
Other transport unions held strikes in solidarity with subway workers today, leaving Athens without bus, tram, trolleybus or rail services, and causing traffic jams across the city.
Public anger has grown against the strike, which is affecting more than a million commuters in a city of 5 million people.
Subway employees oppose being included in a unified wage scheme for public sector workers drawn up under an austerity programme that would slash their salaries.