Responding to such critics, Mr. Stark said that some outside estimates of the E.C.B.’s exposure to questionable assets were greatly exaggerated. “These risks are manageable,” he said, but declined to say how big the risks were. The bank has purchased Greek bonds on open markets and also accepts them as collateral for low-interest loans to commercial banks.

The German Bundestag on Friday authorized the government to take part in a new aid plan for Greece, but only after Wolfgang Schäuble, the finance minister, promised that taxpayers would not bear the burden alone. “We must insist on participation by the private sector,” Mr. Schäuble said during the debate in the Bundestag, the lower house of Parliament.

German taxpayers resent having to pay to rescue Greece, while Greek citizens are angry at the hardships created by the austerity program that was a condition of aid. The tensions have shaken support for the European Union.

In what seemed an attempt to defuse that tension, Mr. Schäuble took pains to praise Greece’s efforts to modernize its economy while enduring an economic slump. “The extraordinary consolidation effort that Greece has undertaken is often overlooked in the public debate,” he said.

Details of that effort disclosed on Friday included more cutbacks and tax increases.

Over the next few years, the civil service, which employs about 700,000, will be reduced by a quarter, Mr. Papaconstantinou said, adding that the ratio of one new hire for every five departures would become one for 10.

The minister also heralded cuts in Greece’s spending in the military sector, which accounts for about 4 percent of gross domestic product.

The new taxes outlined by the minister include a graded “solidarity tax,” ranging from 1 to 4 percent according to income, with an additional 3 percent tax on the income of civil servants. That money is to go toward an emergency fund for the swelling ranks of the unemployed, currently at 16 percent.