German police detained an 18-year-old man over an attempted arson attack against a synagogue Tuesday which drew a shocked reaction from the country's Jewish community.

The building in the western city of Wuppertal was not damaged in the incident and no one was hurt, a police spokesman said.

One of Germany's newest coal-fired power plants rises here from the banks of a 100-year-old canal that once shipped coal mined from the Ruhr Valley to the world.

Now the coal comes the other way.

A German chemistry professor started on Monday a grueling four-week solo swim down the Rhine river for the benefit of science and the environment.

Self-confessed "mad professor" Andreas Fath, who set off on his 1,231-kilometer (764-mile) adventure with a splash into Switzerland's Lake Toma, plans to swim through Germany and France to reach the river's mouth at the Dutch port of Rotterdam on August 24.

German police have arrested a 52-year-old man suspected of sexually assaulting 175 minors, most of them pre-adolescents, a prosecutor told the DPA news agency on Saturday.

The suspect was detained after clues emerged in the investigation into the disappearance of a 14-year-old mentally handicapped boy who went missing a month ago in a town south of Berlin, said the prosecutor for the eastern city of Cottbus, Petra Hertwig.

U.S. Secretary of State John Kerry and top diplomats from Europe and the Middle East gathered in Paris Saturday called for an extension to a temporary truce currently in force between Israel and Hamas.

Both sides have agreed to a 12-hour "humanitarian" ceasefire in Gaza that started at 0500 GMT Saturday, putting a brief stop to a conflict that has killed more than 1,000 Palestinians -- a large majority of them civilians.

About 1,000 pro-Palestinian demonstrators marched through Berlin Friday, closely watched by police for any banned anti-Semitic slogans and separated from pro-Israel rallies.

More than 1,000 officers were on guard in the rainy capital for the rally against Israel's Gaza offensive that has killed more than 845 people, most of them Palestinian civilians.

German Chancellor Angela Merkel pledged the country's Jewish community Wednesday her unwavering support as she condemned anti-Semitic slurs and threats at pro-Palestinian demonstrations, a government spokesman said.

The spokesman, Georg Streiter, said Germany would not tolerate aggression against the resurgent Jewish population, after protests against the Israeli offensive in Gaza where violent slogans were used.

The foreign ministers of Germany, France and Italy on Tuesday condemned anti-Semitic slurs and violence at pro-Palestinian demonstrations in Europe and pledged to take firm action.

Frank-Walter Steinmeier of Germany, France's Laurent Fabius and Italy's Federica Mogherini issued a joint statement in Brussels warning of a rise in anti-Jewish incidents in Europe during the bloody conflict in Gaza.

The death toll from the crash of a coach carrying Polish holidaymakers outside the German city of Dresden climbed to 11 Monday after another victim succumbed to his injuries, police said.

The crash occurred in the early hours of Saturday morning on the A4 motorway which links Poland and Germany.

Germany's Jewish community on Monday condemned an "explosion of evil and violent hatred of Jews" at a recent string of pro-Palestinian demonstrations in the country.

Protesters waving Palestinian flags and signs of late leader Yasser Arafat have in recent days openly shouted angry anti-Semitic slogans at rallies against Israel's Gaza offensive, according to German media.