The euro tumbled to its lowest level in almost two years as investors dumped riskier European equities amid signs that policy makers were bracing for the financial turmoil that could be unleashed by a Greek exit from the eurozone.

The single currency fell about a percentage point during European trading to its weakest level since the summer of 2010 as European leaders gathered in Brussels for an informal summit last night.

In a sign of how seriously eurozone countries are taking the possibility of a Greek exit from the single currency, it emerged that senior eurozone finance ministry officials had held a conference call on Monday during which each country was asked to detail the contingency planning their treasuries had done to prepare for a Greek departure.