BERLIN - Turkey's bid to become part of Europe has hit another hurdle, thanks to two teenagers who met at a Mediterranean beach resort last spring.

The latest obstacle to Turkey's long attempt to join the European Union arose in April, when the mother of a 13-year-old British girl filed a complaint with Turkish police near the coastal city of Antalya. The woman alleged that her daughter had been sexually assaulted by another vacationing youth after a teenage beach fling got out of hand.

Police arrested Marco Weiss, 17, a German high school student from the town of Uelzen, who had been spending a spring holiday at a resort with his parents. Although Weiss denied wrongdoing, court officials ordered him imprisoned without bail, saying he was a risk to flee the country before the investigation could be completed.

Since then, the German teenager has remained locked up in a Turkish jail, sharing a cell at first with 30 other inmates as his case inched through the courts. His plight has become a cause celebre among sympathetic Germans, prompting angry demonstrations across the country and giving further ammunition to those who already opposed Turkey's campaign to join the 27-nation European Union.

"I can only shout out to the Turkish government: If you do not release the young man, Turkey's road to Europe is still miles away," Volker Kauder, a parliamentary leader for the ruling Christian Democrats, told reporters.

About three million Turkish immigrants and citizens of Turkish descent live in Germany, but the country has had difficulty integrating the newcomers into German society. Turkish complaints of prejudice and discrimination are widespread.

German Foreign Minister Frank-Walter Steinmeier has demanded Weiss' release, calling his arrest "a tragic case that does not leave us unmoved." Other lawmakers have asked E.U. officials in charge of expansion talks with Turkey to intervene. The boy's attorneys have threatened to take up the matter with the European Court of Human Rights.

The criticism has upset Turkish officials, who say they were obliged to investigate the British mother's complaint. They also point out that the Turkish criminal code is almost identical to Germany's - the result of efforts to modernize its legal system and make the country a more suitable candidate to join the E.U.

Meanwhile, Turkish diplomats in Brussels and Berlin have protested what they call improper political interference by German lawmakers. The controversy underscores the awkward, love-hate relationship between fast-growing Turkey, with its 71 million people, and Germany, which has a population of 82 million and is the E.U.'s largest member.

The idea of allowing Turkey to become a full-fledged member of the union is anathema to many Germans, including Chancellor Angela Merkel, who has argued for giving Turkey a "privileged partnership" instead.

Millions of Germans vacation in Turkey each year, particularly at its sparkling resorts along the Mediterranean. But Weiss' arrest has fanned fears and hardened impressions of the country.

"The average people in Germany, they just see the trouble we have with Turkish immigrants in Germany, they see the Marco case, they hear about Catholic priests who are shot in Turkey," he said. "All in all, they say such a country cannot become a member of the European Union because these are critical things that are so deep that it will be hard to change them in 10 to 15 years."