BlackRock is calling for bond holders to write off 80% of the value of Greek, Portuguese and Irish debt, suggesting that recent agreements between European regulators and investors in government debt do not go nearly far enough.

In a note published today from the BlackRock Investment Institute, strategists at the world's largest money manager said: "Our analysis suggests private creditors should write off 75% to 80% of Greek debt to allow for permanent stability. Arguably, holders of Portuguese and Irish debt are in for similar 'haircuts'.