German Chancellor Angela Merkel called on her compatriots to be patient with Greece in its current struggle to overcome a severe debt crisis.

"What hasn't been done in years cannot be done overnight," Merkel told the Sunday edition of Berlin's Tagesspiegel newspaper, pointing to Germany's bid to spruce up infrastructure in former communist East Germany after unification in 1990.

"Remember the reunification process," said Merkel who grew up in East Germany. "How much time it took in the early 1990s to rebuild new administrative infrastructures, share know-how and privatise."

"We must be patient," she said.

Merkel also called on the Greek government of Prime Minister George Papandreou not to waver in his reform drive.

"Greece knows that credit is only available if it meets its obligations," she said.

German Finance Minister Wolfgang Schaeuble however doubts that Greece can avoid bankruptcy and is preparing for a scenario where the debt-stricken nation becomes insolvent, the Spiegel magazine reported on its website Saturday.

Spiegel said that finance ministry officials are contemplating two scenarios should Greece become bankrupt: one where the country stays in the eurozone, and another where it re-introduces its former currency, the drachma.

The finance ministry was not immediately available to comment on the report.

Merkel, in her interview, appealed for greater European integration to resolve the grave debt crises plaguing Greece and other nation's on the continent.

"Greater cooperation is needed. I consider it really is our duty to achieve that," she declared.

"Germany has no real future without Europe," she added.

Merkel spoke after Joaquin Almunia, a vice president of the executive European Commission, assailed Germany, the Netherlands and other European countries for not giving more support to the bailouts of Europe's problem economies.

He also rejected the notion that Greece, unable to service its debts or fully implement sweeping reforms demanded by its bailout partners, could be expelled from the eurozone, as suggested by top Dutch officials.

"There are member states, in particularly some of the most powerful -- Germany, Netherlands, Finland, Austria -- who feel that they don't have this kind of problem," he said Thursday.

The same day Germany's Finance Minister Wolfgang Schaeuble warned Greece must fulfil the conditions required if it wants more help to combat its debt crisis.

Ratcheting up the pressure on Athens, Schaeuble said it was "very premature" to talk about a second bailout package for Greece before it had implemented the reforms required to receive its first full disbursement.