The Swedish business daily Dagens Industri reported Friday that Vattenfall was seeking damages to the tune of about 3.5 billion euros ($4.6 billion).
It said the Swedish energy concern claimed that Germany was responsible for past and future losses amounting to that sum stemming from Berlin's decision in 2011 to shut down Vattenfall's nuclear power plants at Krümmel and Brunsbüttel in northern Germany.
The claim appears to be backed by the Stockholm government. Dagens Industri quoted Sweden's Minister for Financial Markets, Peter Norman, as saying it was "reasonable that Vattenfall makes these demands on the German state over loss of revenue."
Following the 2011 nuclear accident in Fukushima, Japan, the German government decided to immediately shut down eight older reactors and speed up efforts to completely phase out nuclear energy generation by 2022.
Already in May this year, the Swedish energy group, which is partly state-owned, filed for arbitration at the International Centre for Settlement of Investment Disputes (ICSID) in Washington.
A Vattenfall spokesman told German news agency dpa on Friday that the arbitration process was still at an early stage, and that the group would not comment on the amount of damages it sought.
Alongside the German utilities E.on and RWE, Vattenfall has been affected most by Germany's decision to gradually replace nuclear and fossil fuel power with renewable forms of energy. While RWE seeks 2 billion euros in damages for its reactors already or soon-to-be idled by the government, E.on claims compensation to the tune of 8 billion euros.
uhe/ipj (dpa, dapd)