Greek riot police have used tear gas to disperse angry protesters in Athens, during a march against government cuts to tackle the country's crippling debt.Clashes erupted at the finance ministry and a state TV truck was petrol bombed. A tense stand-off continues, with protesters hurling bottles and rocks.
Thousands of Greeks are taking part in May Day rallies called by trade unions and left-wing parties.
The EU is demanding the austerity cuts in exchange for a huge bail-out deal.
The rescue package is expected to amount to as much as 120bn euros (£100bn; $160bn) over three years.
The full details of the bail-out are expected to be revealed on Sunday if the Eurozone leaders finally sign off the deal, which is designed to prevent Greece from defaulting on its enormous debt obligations.
'Unpopular measures'
Hoards of angry protesters marched through Athens shouting: "Hands off our rights! IMF and EU Commission out!"
Ericos Finalis, who was taking part in the march, described the planned government cutbacks as "the biggest attack on workers for centuries".
"They want to return us to the 19th Century - this is not going to be a battle but a war that will last for months or even years," he was quoted by AFP as saying.
Another protester, Marina Yotis, told AFP: "Nobody knows what really is going to happen but people know that there is no other way than to come down into the streets and protest."
During the protests, a prominent hotel was vandalised in the central Syntagma square.
There were reports of similar scenes in the northern city of Thessaloniki as youths attacked banks and business premises with iron bars.
There is huge public resistance to the wage cuts, tax rises and pension reductions that are expected to be implemented.
Our correspondent says the unions hope that the rallies will demonstrate to the government, the Eurozone, the IMF and the international markets, that they can mobilise enough "troops" to defeat the new austerity programme.
Greek Prime Minister George Papandreou is expected to announce details of the cuts once the rescue package is approved.
He says the loan is essential to save the country and protect its future, and has warned citizens to brace themselves for a period of hardship.
He has said he will not weaken despite opposition and the political cost of the unpopular measures.
