More Volkswagen shareholders came forward Thursday to sue the German automobile giant over its emissions-cheating scandal, bringing total damages sought so far in Germany alone to more than five billion euros ($5.6 billion).

Two law firms said they had filed claims on behalf of VW shareholders seeking a total of 2.5 billion euros in damages and interest.

That came on top of more than 3 billion euros claimed by 278 plaintiffs who lodged their complaint last week at the court of Brunswick, a northern city close to VW's headquarters in Wolfsburg.

VW, which until recently entertained ambitions of becoming the world's biggest carmaker, has been plunged into its deepest-ever crisis by revelations last September that it installed emissions-cheating software into 11 million diesel engines worldwide.

On top of still unquantifiable regulatory fines from several countries, VW is facing a slew of legal suits, notably in the US and Germany, from angry car owners, as well as from shareholders seeking damages for the massive loss in the value of their shares since September.

Just days after the the scandal went public, the group's stocks plunged as much as 40 percent.

The shareholders say the carmaker knew about the irregularities long before the scandal broke and should have informed stock owners much earlier because the company must have known it would affect the share price.

But VW has repeatedly reiterated that its management board fulfilled its disclosure obligation under German capital markets law.

It argues that none of its top bosses could have known of the full extent of the scandal until it broke in September 2015.