Billionaire investor George Soros has warned a Greek default is "inevitable", and EU leaders must adopt a plan B to stem contagion to the rest of Europe.
Senior European Union (EU) officials are set to meet later on Monday to discuss the eurozone's continuing debt woes.
The FTSE 100 fell below the 6,000 level in mid-morning trading as European markets absorbed Moody's downgrade of Portuguese debt to 'junk' status.
F&C's director of global strategy Ted Scott on the changing role of the ECB during the debt crisis.
The euro slumped today as eurozone finance ministers postponed Greece's €12bn bailout package until the country implements tougher austerity measures to curb its soaring deficit.
Announcing a haircut on Greek bond holdings would help restore a positive mood to bond markets, which have largely priced in such a move, said DWS Investments' CIO Asoka Wöhrmann.
Tension between the European Central Bank and the German government has intensified as Jean-Claude Trichet hit back at the German finance minister's claims Greek government bondholders should contribute to a new aid programme.
As the euro crisis staggers on, Greek EU commissioner Maria Damanaki has raised the prospect of her country being forced out of the eurozone if it does not quickly assert control over its wayward public finances.
Eurozone inflation fell to a lower-than-expected 2.7% in May.