FRANKFURT (Reuters) - Porsche SE <PSHG_p.DE>, the main shareholder of Volkswagen (VW) <VOWG_p.DE>, is facing lawsuits from investors claiming the firm did not disclose the financial risks of VW's emissions scandal uncovered a year ago.

A spokesman at Porsche SE said on Tuesday Frankfurt-based law firm Nieding + Barth had filed 12 lawsuits against the firm which controls 52.2 percent of VW's voting shares, while lawyer Andreas Tilp has submitted another three suits.

Tilp, who has represented investors in many German cases over capital market-disclosure issues, has also been pushing a case against VW filed on behalf of hundreds of investors and worth over 3 billion euros ($3.37 billion).

"We consider all complaints to be unfounded," the Porsche spokesman said, noting that as a holding company, Porsche SE is principally not involved in VW's operating business.

The Porsche investors claim they lost out from the fall in Porsche SE preference shares after VW's manipulations were brought to light by authorities in the United States last September.

The regional court in Stuttgart, where Porsche is based, has received 80 lawsuits targeting Porsche and VW, Germany's Stuttgarter Zeitung reported earlier on Tuesday, citing a spokeswoman at the court.

VW, Europe's largest automaker, is also caught up in legal action in the United States, South Korea and elsewhere and is facing billions of dollars in costs related to its emissions-test manipulations, making it the biggest scandal in VW's history.

(Reporting by Ilona Wissenbach; Writing by Andreas Cremer; editing by Susan Thomas)