Seven Austrian neo-Nazis were sentenced to up to six years in prison in a case the judge said should serve as an example to others in the country, which has a Nazi past.

The members of the so-called Objekt 21, which witnesses linked to an illegal prostitution network, were convicted late on Monday of "re-engagement with National Socialism" - a crime in Austria since 1947.

Part of Adolf Hitler's Third Reich in 1938-45, Austria became democratic after World War Two and passed an anti-Nazi Prohibition Act. It was broadened in 1992 to include Holocaust denial and the belittlement of any Nazi atrocities.

Evidence aired at the trial in Upper Austria province included a video in which the neo-Nazi group members were shown giving "Sieg Heil" salutes in their meeting house, which they called the "arms factory", the Austria Press Agency reported.

Police said Object 21 had maintained a reign of terror in the region for years with arson attacks, weapons and drugs dealing and illegal prostitution among other crimes, and had been under surveillance since 2009.

APA quoted the presiding judge as saying the sentences were meant to have a "preventative" impact on anyone tempted by neo-Nazism. A court spokeswoman said investigations continued into suspected crimes by other gang members.

The two main perpetrators were sentenced to four and six years in jail, and said they would appeal. The others were given sentences of between 18 months and two and a half years, APA reported. All seven had pleaded not guilty.

In its 2012 annual report, Austria's BVT counter-terrorism agency played down the neo-Nazi threat, saying a legal crackdown had deprived the revisionist movement of its leaders.

With their suspected ringleaders on trial, right-wing radicals kept a low profile but in many regions they were stepping up ties with criminal gangs, the BVT said.

Austria's far-right Freedom Party, which got more than a fifth of the vote in the September general election, rejects neo-Nazi ideology but attracts some sympathizers with its anti-foreigner and anti-Islam rhetoric.

British writer David Irving, a Holocaust denier, spent 2005-06 in an Austrian prison for trivialising the Holocaust and was banned from ever returning to Austria.

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