Spanish bond markets suffered their worst performance this week since the start of the year amid fears that the boost to the eurozone from emergency central bank action, which has sparked a powerful rally, is fading. Spanish bond yields, which move inversely to prices, hit their highest levels since the ECB launched the first of its two three-year loan injections at the end of December to save the eurozone's financial system from a credit crunch. The ECB has pumped more than €1tn into the region's financial system in the two three-year loan tenders. The rise in Spanish yields this week is the biggest since the week ending on January 6. Italian yields also jumped, sparking fears that the effects of the central's bank's emergency action, which triggered a powerful rally in the eurozone debt markets as commercial banks used the cheap ECB loans to buy sovereign debt, is fading. Italian 10-year yields rose to 5.49 per cent, with this week's jump the sharpest since the end of November. Portuguese bonds also came under pressure, with 10-year yields rising to 12.07 per cent. By contrast, German 10-year yields dropped to 1.74 per cent, close to record all-time lows. Germany, the eurozone's biggest economy, remains a haven for investors. Alan Wilde, head of fixed income and currency at Barings, said: "This has been a bad week for Spanish and Italian bond markets and does lead to worries that yields could go on rising. ECB loans have helped sentiment, but the effects may be waning. Although French bond auctions went relatively smoothly on Thursday, concerns centred on the less successful Spanish auctions on Wednesday, where Madrid sold €2.6bn of debt, at the lower end of a targeted range. For the 30-year bond, the yield fell to 3.79 per cent from 3.97 per cent. Yields also rose slightly for 10 and 15-year debt. CDS prices have not been affected by the ECB's loan injections, which has helped the government bond markets by giving the region's banks cheap money that can be used to buy peripheral debt. Italian CDS prices have jumped from 349bp on March 19 to 410bp.