Berlin (AFP) - Germany, which has taken a tough line on Greece, has profited from the country's crisis to the tune of 100 billion euros ($109 billion), according to a new study Monday.

The sum represents money Germany saved through lower interest payments on funds the government borrowed amid investor "flights to safety", the study said.

"These savings exceed the costs of the crisis -- even if Greece were to default on its entire debt," said the private, non-profit Leibniz Institute of Economic Research in its paper.

"Germany has clearly benefited from the Greek crisis."

When investors are faced with turmoil, they typically seek a safe haven for their money, and export champion Germany "disproportionately benefited" from that during the debt crisis, it said.

"Every time financial markets faced negative news on Greece in recent years, interest rates on German government bonds fell, and every time there was good news, they rose."

Germany, the eurozone's effective paymaster, has demanded fiscal discipline and tough economic reforms in Greece in return for consenting to new aid from international creditors.

Finance Minister Wolfgang Schaeuble has opposed a Greek debt write-down while pointing to his own government's balanced budget.

The institute, however, argued that the balanced budget was possible in large part only because of Germany's interest savings amid the Greek debt crisis.

The estimated 100 billion euros Germany had saved since 2010 accounted for over three percent of GDP, said the institute based in the eastern city of Halle.

The bonds of other countries -- including the United States, France and the Netherlands -- had also benefited, but "to a much smaller extent".

Germany's share of the international rescue packages for Greece, including a new loan being negotiated now, came to around 90 billion euros, said the institute.

"Even if Greece doesn't pay back a single cent, the German public purse has benefited financially from the crisis," said the institute.

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Greece and its creditors -- the European Central Bank, the International Monetary Fund and the European Stability Mechanism -- are working on the draft of a crucial new bailout of up to 86 billion euros ($94 billion) in exchange for further reforms.

They aim for a deal before the debt-ridden country must repay 3.4 billion euros to the ECB on August 20.

Both sides have indicated that the talks were going well, which would pave the way for the Greek parliament and eurozone finance ministers to approve the agreement ahead of that deadline.

However Germany on Monday warned that negotiations over a third bailout for Greece must emphasise "thoroughness over speed".

"A quick conclusion to the negotiations would of course be desirable but we must not forget that we are discussing a three-year programme, in other words a programme with a wide-ranging list of reforms," government spokesman Steffen Seibert told reporters.