Athens (AFP) - Greek Prime Minister Alexis Tsipras said Sunday the country had a "moral obligation" to claim reparations from Germany for the damages wrought by the Nazis during World War II.

Greece had "a moral obligation to our people, to history, to all European peoples who fought and gave their blood against Nazism," he said in a key address to parliament.

Berlin has already sounded a firm "no" to requests for reparations nearly 70 years after the end of the war, but Tsipras and his radical left party have vowed to tackle the issue.

"Our historical obligation is to claim the occupation loan and reparations," the new PM said, referring to Germany's four-year occupation of Greece and a war-time loan which the Third Reich forced the Greek central bank to give it which ruined the country financially.

Tsipras's anti-austerity Syriza party claims Germany owes it around 162 billion euros ($183 billion) -- or around half the country's public debt, which stands at over 315 billion euros.

The issue risks aggravating already strained ties between Athens and Berlin, as Tsipras bids to reverse austerity measures imposed by its international creditors.

The Nazi regime ended up bleeding Greece dry. The loan to the Third Reich was for 476 million Reichsmarks, which was valued at $8.25 billion in a 2012 German Bundestag lower house of parliament report.