Hundreds of far right and left-wing militants clashed with police in Berlin until the early hours of Saturday morning, in what authorities are calling the worst violence the city has experienced in four years.

On Saturday, police reported they made 289 arrests, more than double the number from last year. Around 270 police were injured during the protests.

The head of Germany’s police union (GdP), Konrad Freiberg said the situation has proven this is a new breed of violence.

"It’s just a question of time until someone gets killed," he said. "The far-right people view the police as their new target of hatred. They prey on the police and are trying to start violent riots."

Freiberg said he expects the risk for riot police is going to increase.

The Social Democrats politician, Ehrhard Koerting, echoing the message, said, "the climate has gotten more rough" .

Violence around the country

Elsewhere in Germany, protests turned violent in the cities of Hamburg, Dortmund, Mainz, Verden and Ulm.

In Hamburg, rioters and police battled for hours. Demonstrators threw stones and bottles and torched garbage cans, until police turned their water hoses on the group. 23 people were arrested.

In the southern German city of Ulm, left-wing militants threw bottles and stones at a march of about 1,000 neo-Nazis after police were unable to keep them apart. City officials said 29 riot police were injured, one seriously, and 21 demonstrators were hurt.

However, on a brighter note, union officials reported that almost half a million people assembled earlier in the day for peaceful demonstrations across Germany.

The wider European picture

With rising unemployment spreading across Europe, and the effects of last year's market crash and banking meltdown rolling into the real economy, the intensity of May Day marches across Europe was higher than usual.

The worst violence was seen in Turkey, where security forces fired tear gas and water cannon in Istanbul and Ankara. Dozens of police and protesters were hurt and more than 100 youths arrested. Protesters smashed the windows of banks and shops.

In Greece, police fired tear gas against a group of about 300 self-styled anarchists who burned at least one car in the streets of central Athens. The clashes came after more than 6,000 people marched peacefully in rallies through the Greek capital. There were no injuries or arrests.

More than 4,000 police officers were deployed in central Athens to prevent violence, in an attempt to prevent Greece saw its worst riots in decades in December which were fuelled by discontent with a slowing economy and high youth unemployment.

Unemployment is rising for the first time since 2004 in Greece as the economy slows and, according to forecasts from the International Monetary Fund, may even contract in 2009 for the first time in 15 years.

United rallies in France

In France -- where massive rallies have already been held on numerous occasions this year -- protests on May Day were largely peaceful.

Unions estimate some 1.2 million took part in 300 marches nationwide, although police said the figure was only 465,000.

In what were the first united May Day rallies since the end of World War Two, the leaders of the country's eight main unions linked arms to lead the demonstrators through Paris.

With France's left-wing opposition, the union leaders jointly called for the day to be turned into a "historic" protest to demand that President Sarkozy's government arrange more help for workers and families hit by the slowdown.

Even staff in management positions joined the marches.

"It is absolutely not in our tradition to protest on May 1, but given the economic context in France and crisis, we decided to join in," said Carole Couvert, a leader of the CFE-CGC union for executives.

Thousands turn out in Spain, Italians remember quake victims

Tens of thousands turned out for demonstrations across Spain, which has the EU's highest jobless rate, 17.3 per cent.

Speakers told more than 10,000 people at a rally in Madrid that the crisis was Spain's worst in 15 years. Union leaders did not rule out a general strike if the unions were not invited to be involved in a dialogue over how to revive the economy.

Meanwhile, Italian union leaders held their rally in the town of L'Aquila, in a show of solidarity after an earthquake there killed nearly 300 people in early April.

"The choice of (L'Aquila) was made as a sign of care and closeness with the workers and the victims of the earthquake," CGIL union leader Guglielmo Epifani said.