BERLIN (AP) — A string of attacks in the eastern town of Nauen near Berlin was likely committed by an anti-immigrant "guerrilla" group led by a local member of Germany's biggest far-right party, officials said Friday.

Their alleged crimes included an arson attack in August on a gym intended as temporary housing for refugees. Nobody was injured in the fire but the building was destroyed in what authorities described as the worst attack on a refugee shelter in the state for over 20 years.

Police on Tuesday arrested a local councilman for the National Democratic Party who is suspected of forming a "criminal organization" intent on committing crimes against migrants and foreigners, according to prosecutor in the eastern state of Brandenburg.

"One gets the impression that a kind of 'right wing urban guerrilla' was active in Nauen over the past year," said Karl-Heinz Schroeter, Brandenburg's interior minister. The group is also suspected of setting alight a Polish man's car, storming a local council meeting and damaging offices of a left-wing party.

The alleged ringleader, 29-year-old NPD councilman Maik Schneider, was arrested the same day Germany's highest court opened hearings on a bid to outlaw the party. Germany's 16 states claim the NPD promotes a racist and anti-Semitic agenda. A ban would prevent it from receiving state funding, which political parties are entitled to.

Germany has seen a surge in far-right attacks over the past year. Figures obtained by The Associated Press put the number of crimes committed against refugee homes last year at 1,029, way ahead of the previous year's 199.

That trend has shown no sign of abating in the first two months of 2016, as Germany continues to grapple with an unprecedented influx of people fleeing war and poverty. Federal police records provided to the AP listed 181 crimes by the end of February, including 25 cases of arson.

Authorities say most of the attacks were committed by people without previously known links to far-right groups.