Striking Greek workers grounded flights, shut down schools and paralysed public transport as protests against austerity measures to dig Greece out of a debt crisis culminated in a nationwide walkout.
Dozens of protestors have thrown several fire bombs at two luxury hotels in the central Syntagma square outside parliament, also setting a car on fire.
Police returned with several rounds of teargas, filling the square with smoke.
Some 15,000 protestors according to police estimates marched in separate Athens demonstrations at the call of the main public and private-sector unions.
The largest unions were hoping for a big turnout to demonstrate their opposition to the government, which is pushing through tough reforms in return for a €110bn EU/IMF bailout.
But with a comfortable parliamentary majority, and future bailout instalments at stake, the ruling socialists are unlikely to reverse course.
Early this morning the 300-seat house voted into law measures that cut wages in state-owned bus and railway companies and weakened the power of collective bargaining to allow company-level deals to prevail.
'We need to send the government a message that we will not accept measures that lead us only to poverty and unemployment,' Ilias Iliopoulos, general secretary at the civil servants' union ADEDY, said.
'After the vote late last night on the worst labour relations ever in Greece, we are warning of more action after the holidays. We will not yield, we will prevail.'
Prime Minister George Papandreou expelled a deputy from his parliamentary team for failing to back the government in the vote. But his party still commands a comfortable 156 votes, with more belt-tightening ahead in the 2011 budget next week.
Today, ships remain docked at ports, hospitals are working on skeleton staff and ministries are shut down, as civil servants and private sector workers stay away.
With journalists joining the strike, there is no news on TV or radio stations.
'It is good that people take to the streets. They have taken away our rights. Patience has its limits, we have kids and loans to pay,' according to bank employee George Mihalopoulos, 57, as he waited for a protest rally to start.
