Factbox: European workers hold anti-austerity protests

LONDON (Reuters) - Greek riot police fired teargas at protesters in Athens during a nationwide strike on Tuesday.

Unions representing about 2.5 million workers, half the workforce, have backed the strike. Trade unions have said they will hold a "European Day of Action" on September 29 to protest against spending cuts.

Here are details of some of the major protests in euro zone countries whose economies are saddled with high debt levels.

* GREECE - About 10,000 people took part in marches across Athens during a nationwide strike on Tuesday -- the fifth joint strike called by public and private sector unions this year. A group of about 150 black-hooded youths threw petrol bombs at police guarding the parliament building in Athens.

-- On June 23 communist trade unionists blocked travelers from boarding ships at Greece's largest port, stranding tourist ferries as part of protests against austerity measures in the debt-choked country. In Athens, 5,000 communists staged a march.

-- On June 5 about 3,000 anti-austerity protesters marched peacefully through Athens, far fewer than in the May protests.

-- Thousands of strikers marched peacefully to parliament on May 20 in protest against austerity measures.

-- Public sector workers held a 48-hour nationwide strike on May 4-5. On May 5, a 50,000-strong protest in Athens led to violence. Demonstrators fought with police and three people were killed in a petrol bomb attack on a bank.

* SPAIN - Spanish workers shut down Madrid's metro system on Tuesday in anger at a 5 percent public sector pay cut.

-- On June 22, Prime Minister Jose Luis Rodriguez Zapatero's minority government won approval for its labor reform bill in parliament after opposition parties abstained.

-- A week earlier, Spain's largest unions announced they would hold a general strike on September 29.

-- A one-day protest was called for June 8 and the country's two largest unions said up to 75 percent of the 2.3 million public sector workers did not turn up for work.

-- On May 27, the government won parliamentary approval for a 15-billion-euro austerity package by a single vote.

* ITALY - The CGIL, Italy's biggest union with 6 million members, held rallies in Rome, Milan and other cities on June 25 to try to force the government to redraft a 25-billion-euro austerity package, which Prime Minister Silvio Berlusconi says is an essential part of European efforts to save the euro.

-- Thousands marched in Rome on June 12 to protest against austerity measures that include cuts in funding to local authorities and freezing the salaries of public sector workers.

* FRANCE - In a challenge to President Nicolas Sarkozy, French unions held nationwide strikes on June 24 and hundreds of thousands of workers took to the streets to protest against plans to raise the retirement age to 62.

-- Bernard Thibault, the head of the CGT, France's largest union, estimated at least 2 million protesters had joined about 200 rallies throughout the country and said this would increase pressure on the government.

-- Sarkozy's government has vowed not to back down on the centerpiece of its reform -- raising the age of retirement to 62 from 60 by 2018 -- saying the move is needed to prevent the pension system from going bust and sinking state finances.

* GERMANY - Tens of thousands protested on June 12 against Germany's biggest austerity drive since World War Two.

-- On June 7, Chancellor Angela Merkel's cabinet unveiled plans for 80 billion euros ($96.30 billion) in budget cuts and taxes over four years.

* PORTUGAL - Tens of thousands marched in Lisbon on May 29 against government austerity measures and the leader of the biggest union vowed to intensify resistance, but stopped short of calling a strike. The rally was the first display of popular discontent since May 13, when the government announced a package including tax rises and cuts in pay and spending.

-- The government and opposition agreed to cut the deficit, partly by imposing 5 percent pay cuts on senior public sector staff and politicians. The deficit is targeted to fall from 9.4 percent of gross domestic product in 2009 to 7.3 percent in 2010 and 4.6 percent in 2011.

(Editing by Mark Trevelyan)