The global banking group that negotiated Greece\'s massive debt writedown called on holdout creditors to sign on to the deal Tuesday, saying it would help Athens restore its financial viability. The Institute of International Finance, which negotiated the pact for private investors to write off more than half of 206 billion euros ($270 billion) in Greek debt they hold, said 96 percent of creditors had agreed to participate. That participation \"reflects the view of many investors that the terms and conditions of the exchange represent a much better outcome than the possible alternatives, given the unique circumstances that Greece faces,\" IIF chief Charles Dallara and his fellow negotiator, Jean Lemierre of BNP Paribas, said in a statement. However, they added, \"Full participation in the exchange by all private holders would greatly assist Greece in focusing on implementing the necessary reforms.\" \"This would help rebuild confidence and stability in financial markets, to the benefit of all, and facilitate the process of restoring Greece\'s creditworthiness.\" Greece\'s finance ministry revealed on April 2 that 11 financial institutions, holding about 6.4 billion euros in Greek debt, had declined to take part in the write-off, which involves swapping old bonds for new ones, and that other debt holders had yet to decide. The ministry has postponed the deadline for joining the debt deal until April 20.