Reuters quoted Chancellor Angela Merkel as saying she would welcome a contribution from Germany's private sector to support a Greek rescue package and acknowledged the public outrage over the damage caused by market speculation. In an interview to appear in Bild am Sonntag newspaper on Sunday, Merkel also said in future countries should face sanctions and even be stripped of EU voting rights if they fail to adhere to euro Stability Pact rules on debt and deficits. "I would very much welcome the voluntary participation from banks," Merkel said, according to an advance interview excerpt. Deutsche Bank Chief Executive Josef Ackermann is helping coordinate German private sector efforts to support the rescue, a senior banking source told Reuters on Friday. The move would make it easier for political leaders to sell a bailout to the German public ahead of a key state election. A consortium has already pledged to contribute 1-2 billion euros ($1.3-2.6 billion) toward the effort, although no formal agreement has been struck, the source said, declining to give details on how the plan would work. Ackermann, one of Germany's top executives and chairman of the Institute of International Finance bank lobby, got involved in helping to assemble the consortium after a conversation with German Finance Minister Wolfgang Schaeuble, the person said. Deutsche Bank declined to comment on the plan, which would be the first sign of private-sector involvement in the rescue. But Sigmar Gabriel, leader of the main opposition Social Democrats (SPD), ridiculed Merkel's efforts to haul the private sector into the Greek rescue with "one-off" donations. "It's nothing more than a placebo," Gabriel told the Neue Westfaelische newspaper on Saturday. "We need more than a one-off donation of a couple billion euros. We need a lasting involvement from the financial markets. These banks and speculators caused these disastrously high debts." Germany is preparing to agree to contribute to a euro zone/International Monetary Fund aid package for debt-stricken Greece once IMF and European officials have agreed an austerity package for Athens. Berlin expects that to happen this weekend. Aware that the German public remains wary of helping Greece, Merkel also told Bild am Sonntag it was essential that the stability criteria be tightened in the future. "It must be possible in the future that a country that fails to live up to its obligations should be, at least temporarily, stripped of its voting rights," Merkel told the best-selling tabloid. "For Germany that will be essential." Merkel said the Stability Pact will be strengthened. -- SPA