Ten-year Portuguese bond yields fell to a low of 3.197 percent and were last down 10 basis points on the day, outperforming euro zone peers. That closed the gap with top-rated German Bund yields to its tightest in just over a year at 279 basis points.

Easing concerns about the euro zone's future following France's presidential elections and stronger data has boosted sentiment towards debt on its periphery. Data earlier this week showed Portugal's economy grew at its strongest pace in a decade in the first quarter, expanding 2.8 percent from a year earlier.