Slovenia's short-term borrowing costs fell further into negative territory on Tuesday when it sold 49 million euros ($55 million) of treasury bills, close to the initial target of 50 million euros, the finance ministry said in an auction report.

It sold 28 million euros of 18-month bills at a yield of -0.19 percent versus -0.05 percent at the previous auction of such bills in April. It also sold 21 million euros of 12-month bills at a yield of -0.25 percent, down from -0.20 percent in September.

Total demand reached 242 million euros. Analysts said yields fell mainly due to the expansive monetary policy of the European Central Bank. No further treasury bill auctions are planned for this year.