VIENNA (Reuters) - A former regional head of Austria's conservative People's Party (OVP) was sentenced to 5-1/2 years in jail in a corruption case that could hit support for his movement, part of the country's ruling coalition, in elections next year.

Josef Martinz, who led the party in the province of Carinthia, and three others were convicted in a breach of trust case that centered on a scheme to milk money from the sale of state bank Hypo Alpe Adria in 2007.

The hearing followed a series of corruption scandals that have dented confidence in public officials and prompted Austria's parliament in June to tighten up rules on politicians' finances.

"The sentences in the case are brutal, but necessary," the Oesterreich tabloid said in an editorial.

The judge allowed the men to remain free pending an appeal against their sentences.

The tough verdicts late on Monday come as a top aide to Chancellor Werner Faymann and the country's environment minister face a parliamentary investigative panel on Tuesday looking into allegations of high-level corruption.

Martinz resigned in July after admitting in court he took part in a scheme to claw back for party coffers part of a 6 million euro fee paid to a tax adviser on the sale. But he said he was innocent of the breach of trust charge.

After the hearing he told journalists the verdict was "a nightmare".

Tax adviser Dietrich Birnbacher and two state officials involved in the bank's sale were also sentenced to up to three years.

The trial heard Birnbacher had confessed and implicated other local politicians in Carinthia, a stronghold of the far-right Freedom Party, which had made strong gains in opinion polls against the ruling national coalition of the Social Democrats and the OVP.

Political analysts say the case could hit support for the OVP, which has already been losing voters to the new Team Stronach party launched by euroskeptic billionaire Frank Stronach.

Members of the rightist Freedom Party of Carinthia (FPK), which governs with the OVP in the province, have said they had no involvement in the scandal.

Former Carinthia Governor Joerg Haider, the right-wing leader who died in 2008, was an architect of the 1.6 billion euro sale of Hypo Alpe Adria to Germany's BayernLB. Birnbacher told the court Haider also sought to get kickbacks from the deal.

(Reporting by Michael Shields; Editing by Andrew Heavens)