The prospect of a eurozone break-up has unnerved investors of all types in recent months, triggering a sharp sell-off in European equities, a jump in the bond yields of peripheral eurozone governments and a slide in the value of the euro.

The uncertainty over Greece's future in the eurozone -- which is coming to a head with a crucial election this weekend -- has combined with a banking crisis in Spain to undermine investor confidence.

That has already prompted some sovereigns to diversify away from the euro. The Swiss National Bank revealed last month that it had doubled its holdings of sterling in the first quarter of the year as it reduced its exposure to the euro. Analysts and traders say that other reserve managers have been doing the same thing.