Violence flared as thousands of protesters took to the streets of Athens in the latest general strike – causing more misery for tourists.
Police fired tear gas as a minority of protesters threw sticks, bottles and stones at officers and set rubbish bins on fire.
Running clashes left seven policemen injured and 13 demonstrators were detained with six subsequently arrested.
Rioters armed with wooden clubs made repeated attacks on police and smashed bus stops and phone booths as well as breaking windows shops and banks.
Riot police chased demonstrators into a main subway station, and one photo journalist reported seeing police detain a young man in a subway car, spraying him with pepper spray.
The violence came as some 10,000 people took part in a demonstration during a 24-hour strike organised by the country’s two main labour unions.
They are opposing drastic changes to pension and labour reforms, proposed in an attempt to control Greece’s spiralling debt problems.
The action shut down transport links and services causing problems for many visiting tourists.
Hundreds of holidaymakers were left stranded by a blockade at the country’s busiest port of Piraeus in Athens.
The blockade was created by some 500 communist-affiliated trade unionists who stormed passenger entry points, stopping a fleet of ferries from sailing to the Greek islands.
Recurring strikes, including deadly demonstrations and mobs of militant workers ambushing ports and popular tourist venues, have eclipsed Greece’s image as a serene, sun-soaked paradise.
The authorities, fearing fresh unrest, sent scores of police in riot gear and the coastguard to seal and shield Piraeus, allowing only passengers with tickets to enter the port’s sprawling premises.
“But that apparently agitated them,” coastguard official Sofia Natsios told Sky News Online.
“They have since broken a number of passenger gates, blocking about seven ferries bound for nearby islands.
Two other ferries bound for popular Aegean islands, including Mykonos and Paros, also called off scheduled departures, Ms Natsios said, as striking dock workers refused to comply with a court ruling that their action was illegal and abusive.
Greece, like its recession-hit Mediterranean neighbours, Spain, Italy and Portugal, relies heavily on tourism which employs one in every five Greeks.
The country’s main tourist bases are Germany and Britain. Some two million tourists visited Greece from each of those nations last year. This season, though, fewer are likely to return.
Last week, a similar protest left thousand of of holidaymakers stranded at the port, one of the busiest in the Mediterranean.
In the centre of Athens, the demonstrations caused chaos as state offices, banks and municipal offices remained shut.
The transport infrastructure also ground to a halt and dozens of domestic flights were cancelled.
Workers are opposing draft legislation raising the retirement age, scrapping pension benefits and making it easier and cheaper for companies to get rid of staff.
The reforms, which parliament is beginning to debate, are part of a list of conditions Athens signed up to last month to secure the first instalment of a £90bn bail-out package, patched together by the EU and the International Monetary Fund.