The Finnish government told parliament that Helsinki and its Dutch allies would block the euro zone's permanent bailout fund buying bonds in secondary markets.
Euro zone leaders agreed last Friday that rescue funds could be used in a "flexible and efficient manner" to lower government borrowing costs. Their statement gave no further detail.
The euro fell and safe-haven German Bunds reversed losses on news of the Finnish statement, which raised fears that the latest deal which drew a positive initial market reaction could be fraying.
Several previous market rallies after euro zone crisis agreements have fizzled within a day or two as investors have fretted about the lack of detail, the risk of delay and national vetoes, or the inadequate size of the rescue funds available.
The German parliament has voted in favor of the EU’s permanent bailout scheme and more lenient budget rules. Chancellor Merkel has been criticized with making a U turn in policy, easing borrowing costs on flagging banks without additional austerity.
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