Researchers and sports officials said right-wing extremists were volunteering to become coaches or club members, setting up their own sports clubs or organizing youth leisure activities. "They're helping out and building up trust so they can get their message across later," said a spokesman for the German Olympic Sports Federation (DOSB).

Sports clubs are vulnerable because there is a growing shortage of people willing to do voluntary work, said Gunter Pilz, a sociologist who has researched far-right influence in youth sport.

'A Sense of Belonging'

In some rural areas of eastern Germany, such as Mecklenburg Western-Pomerania, the nearest swimming pool or youth center can be many miles away. "The right-wingers jump into these gaps and offer youths something," said Gerd Wagner, a member of the fan supporters' group KOS.

He said young people are given "a sense of belonging and being appreciated" and are fed Nazi ideology and racist views at the same time.

Experts said the far-right infiltration of sports isn't just happening in eastern Germany, which has a relatively strong neo-Nazi presence, but also in the west.

"Attempts are being made to misuse sport as a platform to spread right-wing extremist ideology. We're opposing that vehemently," the president of the DOSB, Thomas Bach, said in a statement released after a conference in Berlin by government officials and representatives of the top sports federations including the German Football Association.

The conference agreed to improve coordination between the government, anti-racism groups and sports federations and to provide more information and advice to help clubs keep extremists out.