A general strike has been called across Greece as protests against planned spending cuts and tax rises continue.
Trains, planes and ferries are at a standstill as transport workers join public sector workers who began their own 48-hour strike on Tuesday.
Austerity measures planned in return for a 110bn euro (£95bn) international rescue package for the debt-struck economy have sparked widespread anger.
The Greek parliament is to vote on the measures by the end of the week.
Measures include wage freezes, pension cuts and tax rises. They aim to achieve fresh budget cuts of 30bn euros over three years, with the goal of cutting Greece’s public deficit to less than 3% of GDP by 2014. It currently stands at 13.6%.
The general strike is the third to hit Greece in as many months.
Meanwhile, the German parliament has begun considering the bail-out plan for Greece.
Chancellor Angela Merkel will defend her government’s decision to take part in the deal agreed by European finance ministers, which requires Germany to pay the largest proportion of the loans to be made available to Greece.
Flights in and out of Greece stopped at midnight, and trains and ferries were not running early on Wednesday.
Schools, hospitals, and many offices are expected to remain shut.
A mass rally is planned in central Athens before protest marches pass through the city, with parliament expected to again be a focus of attention.
The demonstration was largely peaceful. But some scuffles broke out near the parliament building, with demonstrators throwing stones at riot police, who responded with pepper spray.
Dozens of Communist protesters broke into the ancient Acropolis at dawn on Tuesday, draping giant banners on the Parthenon temple reading: “Peoples of Europe Rise Up.”
In other signs of discontent, on Monday a group of teachers forced their way into the main state broadcaster’s studios in Athens to protest about education cuts.
Union leaders say the cuts target low-income Greeks.
“There are other things the [government] can do, before taking money from a pensioner who earns 500 euros (£430) a month,” Spyros Papaspyros, leader of the public servants’ union ADEDY, told Greek private television. The EU has agreed to provide 80bn euros (£69bn) in funding, while the rest will come from the International Monetary Fund (IMF).
The deal is designed to prevent Greece from defaulting on its massive debt.
However, it must first be approved by some parliaments in the 15 other eurozone countries.
In return for the loans, Greece will make major austerity cuts which Prime Minister George Papandreou said involved “great sacrifices”.