Italy's borrowing costs rose sharply on Wednesday, reflecting fresh unease on the debt market at an auction which raised eight billion euros ($10.45 billion) in six-month bonds.
Rates almost doubled, rising to 1.052 percent from 0.538 percent at the last similar operation on May 29, while demand was down, according to the Bank of Italy.
It was the highest rate for six-month bonds to be paid since February, Dow Jones Newswires said, and followed a disappointing bond sale with raised interest rates on Tuesday.
The results increase pressure on Prime Minister Enrico Letta's government as it bids to push through new measures to boost growth in the recession-hit government.
Attention will now focus on a significant five and ten-year bond sale expected on Thursday.