Martin Callanan, Conservative group leader in the European Parliament, said the latest downgrade from Standard and Poor's was a grave blow to the credibility of the eurozone as a whole.

 

He said: "The CRAs have continued to expose the weakness of individual parts of the common currency structure, now they strike at its very heart. But the blame is with the eurozone's leadership, not the agencies.

 

"This proves what we have been saying for weeks - that the December summit was never going to deliver a solution to the crisis. The EU must stop obsessing with treaty change and instead address the fundamental failings at the heart of the euro project.

 

"Finally it is absolute proof that to keep this battered currency afloat they must jettison the economies such as Greece that will otherwise drag it under."