Just days after European policymakers toasted a 109 billion euro ($156 billion) bailout aimed at hauling Greece back from the brink of insolvency, speculation some of its hapless bondholders might opt out of a crucial distressed debt exchange is gathering pace.

Greek creditors in banking, insurance and fund management are baying for more clarity on a proposed 'voluntary' scheme in which debt can be swapped for 15-year or 30-year bonds paying interest Greece can more easily afford, and slashing its debt.