Spain's borrowing costs rose as it tapped the debt market on Wednesday for the first time since the eruption of a corruption scandal that has implicated top members of the ruling Popular Party including Prime Minister Mariano Rajoy.
The Treasury raised 4.61 billion euros ($6.25 billion) in medium- and long-term sovereign bonds, with demand outstripping supply by two to one, the central bank said in a statement.
Leading centre-left newspaper El Pais last week published account ledgers allegedly kept by two former treasurers of the Popular Party that purportedly show that at least a dozen senior party officials, including Rajoy, received payments from a secret slush fund.
The right-leaning Popular Party has denied the allegations, which have sparked calls for Rajoy to resign and have raised questions about his government's ability to implement austerity measures to get Madrid's finances in order.
The Treasury raised 1.95 billion euros in an auction of two-year bonds with the yield rising to 2.823 percent from 2.476 percent at the last similar auction held in January.
It brought in 2.07 billion euros in a sale of five-year bonds with a yield of 4.123 percent, up from 3.77 percent in January and another 593 million euros from the sale of 16-year bonds at a yield of 5.787 percent.
The last time Spain sold a 16-year bond was in January 2010 and the yield this time around is not comparable to that auction.
The Treasury estimates its gross financing needs at 215-230 billion euros in 2013, after it borrowed a total 249.6 billion euros in 2012.