Germany snubbed Greece's call for more than 278 billion euros ($306 billion) in war payments Tuesday, calling it "dumb" to mix World War II claims with Athens' negotiations for more aid.

Economy Minister Sigmar Gabriel said calls for reparations for the brutal four-year Nazi occupation of Greece only hampered progress on efforts to financially shore up Athens as it battles its massive debt mountain.

Making calls for reparations does not advance the race by Greece and its creditors to bolster the country's solvency by even "a millimetre", Gabriel, who is also vice-chancellor, said at an event in Berlin.

"Honestly, I find it dumb," he added.

Greece has an interest in gaining "wiggle room" for its new radical government's policies, Gabriel said, adding: "This changed policy and the wiggle room have absolutely nothing to do with the Second World War and reparations payments."

Greece's fledgling radical-left government that came to power in January has stepped up pressure on Berlin over the emotional and controversial issue of war reparations which it says are a "moral issue" that must still be resolved.

As tempers have flared between debt-mired Greece and the eurozone's effective paymaster over the debt crisis, painful historical memories have resurfaced over the Nazi's bloody and devastating occupation of Greece from 1941.

A junior minister told the Greek parliament on Monday that the figure owed by Germany amounted to more than 278 billion euros, including some 10 billion for a forced loan taken by Nazi occupation forces.

- 'Legally, politically closed' -

Berlin argues that the issue of reparations to Greece has already been settled, and points to payments made in 1960 as part of an agreement with several European governments.

It also maintains that a treaty signed by the two former Germanys with the Allies in 1990 to formally end World War II effectively drew a line under possible future claims for war reparations.

"The government is of the opinion that that is legally and politically closed," a finance ministry spokesman said Tuesday, stressing he was reacting to the issue of reparations' demands generally and not to the figures quoted by Athens.

Greek Prime Minister Alexis Tsipras raised the issue with German Chancellor Angela Merkel on his first visit to Berlin as premier last month.

Greece's parliament has approved a motion to reactivate a special committee to look into war reparations, reimbursement of the forced war loan and the return of archaeological relics seized by German occupation forces.

Tsipras' justice minister said last month that he was prepared to activate a 15-year-old Greek Supreme Court ruling that authorised the seizure of German assets in Greece to pay for wartime atrocities.

Merkel in March said she saw the issue of reparations as "politically and legally resolved" but said Germans were aware "of the atrocities we committed" and took their responsibility for the crimes of the Nazis "very, very seriously".

She told reporters at the time that she would be willing to discuss additional contributions to a German-Greek "future fund" designed to finance programmes fostering reconciliation between the countries.

It was launched last year with an annual budget of one million euros.

Many experts say the dispute has effectively reached a judicial stalemate after related adjudication between Germany and Italy by the International Court of Justice in 2012.

At the time, the United Nations' highest court ruled that Italy had broken international law by allowing its courts to hear civil compensation claims against Germany.

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