Euro zone governments are considering a plan to prevent a Greek default under which private investors would be asked to maintain their exposure to its debt and Athens would receive a new package of EU/IMF aid, Reuters quoted euro zone sources as saying. The sources told Reuters of the new strategy on Thursday after the European Central Bank raised the stakes in its bid to prevent a restructuring of Greek debt by telling governments it would refuse to accept the bonds as collateral in the event of such a move. The threat, made by ECB Executive Board member Juergen Stark at a conference in Athens on Wednesday came after European finance ministers raised the possibility of a "soft restructuring" via debt maturity extensions earlier this week. One source with insight into European discussions on Greek debt said any "soft" or "hard" restructuring that might trigger a "credit event" -- or the payout of default insurance contracts -- was now off the table. Instead of a maturity extension, which might decrease the value of bonds and trigger such an event, banks would be encouraged to maintain their holdings of Greek debt and buy new bonds to replace issues as they matured, the source said. This would be done in combination with a new package of Greek reforms and austerity, as well as more EU/IMF money to secure Greece's funding needs through 2014. -- SPA