* Conservative Interior Minister warns Greece before vote
* Greece must honour promises, Friedrich says
BERLIN, May 26 (Reuters) - Germany will not "pour money into a bottomless pit" and patience with Greece is growing thin ahead of a new election in the Mediterranean country, a conservative member of Chancellor Angela Merkel's cabinet was quoted on Saturday as saying.
Interior Minister Hans-Peter Friedrich told the Leipziger Volkszeitung newspaper that Germany, Europe's largest economy and the biggest contributor to rescue efforts, is glad to help Greece help itself but expects it to honour its agreements.
"We're not willing to pour money into a bottomless pit," he told the newspaper.
"Anyone who wants to see help and solidarity from us has to accept that we expect from that country a certain amount of seriousness and a certain amount of reasonableness."
Friedrich, who has long been a hardliner in Merkel's cabinet on Greece, became the first German minister in February to openly call for the country to leave the euro zone.
While his latest comments appear to be aimed at placating Germans who are increasingly anxious about the Greek situation, they are likely to reopen old wounds with Athens.
Finance Minister Wolfgang Schaeuble also called Greece "a bottomless pit" in February but after being villanised in Athens has since refrained from using the term.
Greece was forced to call a repeat election for June 17 after a May 6 vote left parliament divided between parties that support and oppose austerity conditions attached to a 130-billion-euro ($163 billion) bailout package agreed with the European Union and International Monetary Fund in March.
Anti-bailout parties are expected to repeat their strong performance, opinion polls show, increasing the risk Greece will renege on its austerity pledges, default on its debt and possibly leave the single currency.
Merkel and European Union leaders said at a summit this week they want to keep Greece in the euro zone. But sources told Reuters the Eurogroup Working Group - experts who work for the bloc's finance ministers - had told member states to begin making contingency plans for a Greece exit.
Juergen Fitschen, the designated co-chief executive of Germany's largest commercial bank, Deutsche Bank, was quoted in online editions of German newspapers on Friday calling Greece a "failed state".
"Greece is the only country that we can in my view call a failed state," he said. "It's a corrupt state, its political leadership is corrupt."
Friedrich, a leader in the arch-conservative Christian Social Union (CSU) that is the Bavarian sister party to Merkel's Christian Democrats (CDU), said Greece made a mistake assuming joining the euro would give the country prosperity.
"(They) evidently believed wealth would be automatic if they got their hands on the euro," Friedrich said.
He added "a country needs a currency that matches its economic strength."
Public opinion in Germany is turning against Greece staying in the euro zone. A Politbarometer poll by ZDF TV published on Friday showed only 31 percent want Greece to stay with 60 percent opposed. In a similar ZDF poll in November, 41 percent wanted Greece to stay and 49 percent wanted to see it leave.
Germany's Nobel literature laureate Guenter Grass attacked Europe for its treatment of Greece in a poem published on Saturday in the Sueddeutsche Zeitung newspaper called "Europe's Disgrace".
Greece was being disparaged as a country "below junk value", he wrote, and added it was "close to chaos because you're not fit for the markets".
He said Greece was being "abandoned as a naked debtor in the dock, a country suffers ... and is condemned to poverty."
$1 = 0.7992 euros) (Reporting By Erik Kirschbaum; Editing by Sophie Hares)