* Arrests in Italy, Spain, Portugal; protesters and police clash
* Flights cancelled, factories at standstill in Iberia
* Demonstrations also in Greece, Belgium, France
* Recession deepens in southern Europe, record joblessness
By Feliciano Tisera and Daniel Alvarenga
MADRID/LISBON, Nov 14 Demonstrations turned violent in Spain and Portugal after millions took part in a mostly peaceful general strike on Wednesday in organised labour's biggest Europe-wide challenge to austerity policies since the debt crisis began three years ago.
In Lisbon, marches ended with a level of violence not seen since the crisis began, with police charging demonstrators who hurled stones and bottles, leaving nearly 50 people hurt.
Protesters in Madrid burned rubbish bins, filling the central boulevard with smoke, while in Barcelona demonstrators burned police cars.
Riot police fired rubber bullets to disperse protesters in both cities, where more than 140 people were arrested, including two said by police to be carrying material to make explosives, while more than 70 were reported injured.
Hundreds of flights were cancelled, schools were shut, factories were at a standstill and trains barely ran in Spain and Portugal where unions held their first joint general strike. Stoppages in Belgium interrupted international rail services.
Workers also protested in Greece and France against austerity policies that have taken a heavy economic toll and aggravated mass unemployment.
But the demonstrations organised by the European Trade Union Confederation seemed unlikely to force hard-pressed governments to change their cost-cutting strategies.
"In austerity, there is only depression and unemployment," Fernando Toxo, head of Spain's biggest union, Comisiones Obreras, told a packed Columbus Plaza in central Madrid.
Even non-union workers jointed protests and marches.
"This isn't about politics or unions. This is social and economic. If we have to shut down the country we'll shut it down," said 24-year-old Mariluz Gordillo, a non-unionised phone operator at El Corte Ingles department store in Madrid.
In Rome, scuffles broke out between police in riot gear and demonstrators who threw stones, bottles and fireworks. About 60 demonstrators were detained. Protesters occupied Pisa's mediaeval Leaning Tower for an hour, hanging a banner reading "Rise up. We are not paying for your crisis".
In Portugal and Greece - both rescued with European funds and under strict austerity programmes - the economic downturn sharpened in the third quarter, according to figures released on Wednesday.
Portuguese unemployment jumped to a record 15.8 percent while in Spain, one in four of the workforce is jobless.
Greece's economic output shrank 7.2 percent on an annual basis in the third quarter as the debt-laden country staggers towards its sixth year of depression.
Close to 26 million people are unemployed in the European Union while governments cut spending.
"Things have to change... Money has ended up with all the power and people none. How could this happen?" said Esteban Quesada, 58, a hardware store owner in Barcelona.
Throughout southern Europe governments are trying to put public finances back on track after years of overspending. Portugal and Greece have cut pensions and, with Spain, have slashed public sector wages as well as spending on hospitals and schools. Italy and France are also under pressure to control their budget deficits.
EU Economic and Monetary Affairs Commissioner Olli Rehn praised Spain for making progress in trimming its budget but acknowledged many Spaniards are struggling.
Germany's central bank, the Bundesbank, said in a report on Wednesday that the euro zone debt crisis is still the number one risk to German banks and insurers, and the situation had not improved from last year.
Promises from the European Central Bank to support sovereign bond prices for countries that seek aid have brought some relief to Spain and Italy in the capital markets. On Wednesday Italy sold 3-year bonds at the lowest borrowing cost in two years.
SPAIN TO STAY THE COURSE
The protests seem unlikely to force significant policy shifts. Spanish Economy Minister Luis de Guindos said the government would press on with spending cuts to meet ambitious deficit cutting targets, despite the strike.
Union leaders in Spain said more than 9 million workers had joined the general strike - the second this year.
The government said participation was much lower and many services were functioning normally. Stores opened in many parts of the country, though some had protesters outside.
About 5 million people, or 22 percent of the workforce, are union members in Spain. In Portugal about a quarter of the 5.5 million strong workforce is unionised.
Passions were inflamed when a Spanish woman jumped to her death last week as bailiffs tried to evict her from her home. Spaniards are furious at banks being rescued with public money while ordinary people suffer.
In Portugal, there is growing public and political opposition to austerity measures sought by Prime Minister Pedro Passos Coelho.
Inspectors from the "troika" of the International Monetary Fund, ECB and European Commission - who monitor implementation of bailout conditions - drew the protesters' anger. In Lisbon, thousands gathered in front of parliament shouting "This debt is not ours" and "Out IMF, out troika".
In Spain, protesters jammed cash machines with glue, and plastered anti-government stickers on shop windows. More than 600 flights were cancelled in Spain, mainly by Iberia and budget carrier Vueling. Portugal's TAP cancelled about 45 percent of flights.
In Greece, hundreds of strikers rallied peacefully in central Athens, holding giant Italian, Portuguese and Spanish flags and banners proclaiming "Enough is enough."
In France, trade unions organised marches in more than 100 cities but did not call for a strike.