MILAN, Sept 11 (Reuters) - The threat of a political crisis pushed up Italy's borrowing costs at auction on Wednesday as the world's fourth-largest debtor paid 1.34 percent to sell one-year paper, the highest since December 2012.
Italy had paid 1.053 percent on the same maturity a month ago.
Italy sold the planned 8.5 billion euros in one-year bills. Demand totalled 1.4 times the amount on offer, down from 1.5 times at a similar auction in August.
It also sold 3.0 billion euros of one-off 101-day bills at an average 0.51 percent yield.
The Treasury returns to the market on Thursday offering up to 7.5 billion euros in longer-term bonds.