Greece faced slightly higher borrowing costs yesterday as it sold 390 million euros’ worth of 26-week treasury bills in an auction that drew strong investor interest. The Public Debt Management Agency (PDMA) said the sale, originally planned to raise 300 million euros, was oversubscribed 5.15 times and offered a yield of 4.82 percent. A similar auction on October 12 for 900 million euros had been oversubscribed 4.22 times but had a slightly lower yield of 4.54 percent. Greece began monthly short-term debt issues in September to maintain a presence in the market after its financial crisis effectively blocked it out of the long-term international debt market, with investors demanding prohibitively high interest rates for its bonds. The Greek auction took place amid mounting investor concerns about Ireland’s and Portugal’s ability to bring their public finances under control. This, coupled with fears of subdued economic growth, helped to extend the trend of recent days, with bond yields for these countries rising to fresh highs yesterday. The European Central Bank responded by purchasing Irish and Portuguese government bonds, according to trading sources, but this provided only a brief respite, as spreads widened again after narrowing only slightly. By contrast, Greek spreads stabilized yesterday after narrowing Monday, as results showed the ruling Socialists won Sunday’s local elections in most of Greece’s regions, averting the risk of early general elections. Greek yield spreads over German bunds stood at 8.89 percentage points yesterday, down 0.11 percentage point on the day. Irish and Portuguese yield spreads widened by three and 11 basis points respectively, to 5.52 percentage points and 4.43 percentage points, respectively, Dow Jones reported.