Norway's wealth fund has filed a legal complaint against Volkswagen, as part of a joint legal action over the diesel emissions scandal.

According to Reuters, citing the fund, the complaint was filed with the Braunschweig district court in Germany and becomes part of a law suit on behalf of institutional funds linked with the scandal.

The fund is VW's largest shareholder without holding any positions on its board, and announced its decision to file suit against the company back in May. It holds 1.02% of VW and has long condemned the company's governance in giving 50.7% voting rights to Porsche and Piech families which hold only 31.5% of the capital.

The fund claims to have expressed its concerns over Volkswagen's leadership structure in writing. At the recent annual general meeting, it also voted against VW's proposal to discharge its board members for their 2015 activities, as suggested by the voting records on the company's website. But the fund has voted in favour of a shareholder's proposal to investigate how Volkswagen's management and board handled the emissions scandal, Reuters said.