Greece is now the country with the world's lowest credit-rating after its debt was downgraded today.

Standard and Poor's, the credit-rating agency, lowered Greece's long-term sovereign debt rating by three notches, indicating that it considers a default to be highly likely.

With eurozone politicians considering involving private creditors in a new bail-out and extending maturities on existing loans, Standard and Poor's said this would be classed a default.

In a statement this evening, Standard and Poor's said: "In our view Greece is increasingly likely to restructure its debt in a manner that, under the conditions of any package of additional funding provided by Greece's official creditors, would result in one or more defaults under our criteria."

The announcement sent Greek ten-year bond yields to more than 17%, almost the highest level seen since the introduction of the euro.

How many billions for this result?