German government bonds extended an advance after state-run Athens News Agency reported that six senior members of the Greek ruling party called on Prime Minister George Papandreou to step down.
The 10-year bund yield fell 25 basis points to 1.78 percent at 12:52 p.m. in London.
The yield on two-year Greek notes jumped 575 basis points to 83.49 percent as the price dropped to 36.68 percent of face value.
Italian two-year note yields jumped 68 basis points to 5.68 percent.
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