Striken with debt, Greece has said in recent years that it reserves the right to claim reparations worth several billion euros, saying it was forced to accept unfavourable terms during negotiations in the 1950s.
"The matter remains pending," said Deputy Finance Minister Christos Staikouras on Monday. "Greece has never resigned its rights."
Nonetheless, he called for a "realistic and cool-headed" approach to the prickly issue, which could further sour relations between Germany and Greece.
The four-member working group is expected to submit its report by the end of the year, the ministry said in a statement.
Many in Greece blame Germany for the tough austerity measures currently being enforced as it tries to climb out from under its debt mountain.
Greece has been given international credit lifelines – first for €110 billion in May 2010 and then for €130 billion earlier this year, plus a €107 billion private debt write-off.
Germany is the biggest single donor to Greece's bailout packages.