The last bars of Ravel's "Bolero" had just died away to applause, but when conductor Volker Hartung tried to return to the stage for an encore, dozens of police officers blocked his way and led him from the concert hall in handcuffs.

The German maestro spent the next two nights in jail being questioned for allegedly violating French labor law by underpaying his musicians.

But that, said Hartung, is the whole point -- the musicians are young freelancers who get to travel and perform live, the public pays less for tickets, and another small step is taken toward fulfilling the vision of the founders of the European Union -- free movement of people, goods and services. "I'm trying to give young people a chance to play and earn a living," Hartung said in an interview.

But the influential French and German musicians' unions contend that his use of mostly Eastern Europeans at nonunion wages amounts to exploitation.

Hartung and his orchestra continue to tour, but ever since that February night at Strasbourg's Palais de la Musique, they have been embroiled in a costly and time-consuming legal mess. The conductor said his income was down by 50 percent.

Although France is the only country where Hartung has faced charges, several English churches have denied him the right to perform on their premises. And although he is allowed to operate as usual in Germany, the musicians' union has waged a persistent campaign against him.

The tour that abruptly ended in Strasbourg had already been to Belgium, Luxembourg and Switzerland, where Hartung's hiring practices raised no eyebrows. Hartung says he took extra precautions for the French leg, securing a collective work permit for his orchestra. But it was revoked without explanation in a fax just hours before the concert was set to start and when it was too late to cancel, he said.

Strasbourg is the home of the European Parliament and a symbol of continental harmony. But French officials -- tipped off by the union, Hartung says -- sent about 80 police officers to arrest him.

Hartung, 49, is married to a Frenchwoman and has performed dozens of concerts in France. "I'm not aware that I have impoverished any French artists," he said.

He claims the union, the Syndicat National des Artistes Musiciens de France or SNAM, is persecuting him because he has managed to fill houses charging lower-than-usual prices on their home turf. Other major orchestras charge from $21 to $72 for a seat, but the Cologne New Philharmonic has one price -- $24. It rejects the E.U. formula of state support and job security, relying on box office receipts alone.

A Strasbourg magistrate eventually dropped the charges of hiring illegal workers, but Hartung says he fears the union may come after him again if he performs in France.

The German union has gone as far as to call work in Hartung's orchestra "a kind of modern slavery."

"We are not against Mr. Hartung as a person. We are against his way of organizing classical music," said Gerald Mertens, head of the German union Deutsche Orchestervereinigung. Philippe Gautier, assistant secretary general of SNAM, called Hartung's pay scale "scandalous." He and Mertens cited a figure as low as $35 a day that appeared in the news media after the arrests of Hartung and his wife in Nice, France, in 2004 over performances the couple say were training workshops.

The unions say a unionized German or French musician would be paid $120 to $180 a day. Hartung says he pays $95 to $120 per concert.

Alexander Tschernousov, a Russian-born string bass player in Hartung's orchestra, said he received at least $95 for the Strasbourg concert plus lodging, bus transport and two meals a day.

After the concert, he said, he and fellow musicians were interrogated, instruments in hand. "We're musicians, not criminals," he said.

Volker Hartung conducts the Cologne New Philharmonic.