The short respite brought to euro zone bond markets by the European Central Bank's liquidity-boosting measures has ended, and the central bank will need to resort to more tricks in order to prevent yields from rising to unsustainable levels again, according to analysts.

European Central Bank

With yields on 10-year Spanish bonds rising back to 6 percent for the first time this year on Monday, investors are turning their attention back to the fundamental problems plaguing the currency union, and some are again talking about its disintegration.