International bank regulators gave a second dangerous incentive to banks to lend to these countries, by classifying the debt as a close proxy for money for liquidity-management purposes (or to give protection against the risk of a bank run).

BBC: The eurozone's borrowing costs may stay lethally high

The ex-chairman of HBOS has admitted the bank took on too much risk in the run-up to the financial crisis in 2008.

BBC: HBOS ex-chairman Lord Stevenson admits errors

Without such risk-sharing, though, much of the euro zone could be one bank run away from meltdown.

ECONOMIST: Charlemagne

Sir James Crosby quit as deputy head of the Financial Services Authority (FSA) amid embarrassing questions about risk-taking at the bank he used to run.

ECONOMIST: Bagehot