Ms. Merkel attended a mini-summit in Rome with leaders of the euro zone's other big economies - François Hollande of France, Mariano Rajoy of Spain and Mario Monti of Italy - all of whom want new measures to combat a crisis which shows no signs of abating after more than two and a half years. Heavily outnumbered in the Italian capital, Ms. Merkel now also has to contend with an appeal from the I.M.F., which called late Thursday for the euro area to move swiftly toward a fiscal union including issuance of joint euro zone debt and said the viability of the currency was being questioned. Diplomats and officials said that the intervention of Ms. Lagarde, who is a former finance minister of France, seemed designed to reflect the views of non-European governments, which have consistently urged leaders of euro zone countries to get to grips with the crisis. But they said that the comments might be counter-productive. Ms. Lagarde "has a history of trying to show that she is no longer the voice of the Europeans," said one official not authorized to speak publicly, "but I don't think it's sensible. The more pressure you apply to Merkel, the more she tends to resist, and if you make statements publicly, that makes it more difficult for her to move. Throughout the crisis Ms. Merkel has resisted taking bold steps, aware that as the euro zone's biggest economy Germany's taxpayers risk picking up the tab for the debts of less competitive economies on Europe's periphery. But throughout the crisis Ms. Merkel has often softened her stance at points when the situation has become critical, and she could credibly argue to domestic voters that drastic action was necessary to save the single currency. Nevertheless, euro zone officials cautioned that Ms. Merkel had limited room to move and that fundamental changes to the single currency would, in any event, take time to achieve. In an additional measure to help ailing banks and prevent a credit crunch, the European Central Bank said Friday that it would broaden the collateral it accepts for low-interest loans. The measure will "further support the provision of credit to households and non-financial corporations," the E.C.B. said in a statement. The E.C.B. lowered the credit ratings it requires for some kinds of collateral, for example securities backed by auto or consumer loans. Banks can borrow as much money as they want from the E.C.B. at the benchmark interest rate, currently 1 percent, as long as they can post collateral. Banks in Greece, and many banks in Spain, Ireland and Portugal, are unable to raise funds through normal market channels and depend on the E.C.B. for cash they need to make loans. But some have been running low on collateral, making it harder for businesses and consumers to get loans and undercutting the economy. European stocks, which fell at the opening, had moved up by the afternoon, with the Euro Stoxx 50, a measure of European blue chips, up 0.21 percent. Other European benchmarks were down less than 1 percent, with the exception of the Ibex 35 in Spain, which was up 2.45 percent. Asian stocks closed lower. The Nikkei 225-stock index in Japan fell 0.29 percent, and the Hang Seng index in Hong Kong fell 1.40 percent. The euro traded at $1.2567, down from $1.2660 late Thursday in New York. Italian and Spanish bond yields fell. The 10-year Spanish bond traded to yield 6.359 percent, down 16.8 basis points from Thursday, and the similar Italian bond carried a yield of 5.68 percent, down 3.2 basis points. Jack Ewing in Frankfurt, James Kanter in Luxembourg, Raphael Minder in Madrid and Paul Geitner in Brussels contributed reporting.